What is protein?

Protein is an essential nutrient that you need throughout life. Proteins are the building blocks of life. Protein is in every cell in your body. The basic structure of protein is a chain of amino acids called a polypeptide ¹, ², ³. A protein is a chain of amino acids bound to one another via peptide bonds (chemical bond linking amino acids together to form a protein). When someone eats protein, it is broken down into its amino acids. There are hundreds of amino acids exist in nature, but humans use only 20 amino acids, each with distinct chemical and physical characteristics ¹, ⁴. All amino acids contain an amino group (-NH₂) and a carboxyl group (-COOH). Amino acids that serve as the building blocks of proteins are alpha amino acids (α-amino acids), having both the amino group (-NH₂) and carboxyl group (-COOH) linked to the same carbon atom. In alpha-amino acids (α-amino acids), the two functional groups are bound to a central carbon atom known as the alpha carbon. At the alpha carbon is also a hydrogen atom and a variable side chain, often referred to as the R-group, which gives each amino acid its unique chemical properties (see Figure 1). These amino acids are alpha amino acids and classified based on the properties of their R-groups. Amino acids are not only the building blocks of proteins, but some are also precursors for neurotransmitters (e.g., serotonin, dopamine), signaling molecules (e.g., nitric oxide), and metabolic intermediates (e.g., α-ketoglutarate, oxaloacetate).

Your body needs protein to make, maintain, repair and renew bones, muscles, cartilage, hormones, enzymes, neurotransmitters, vitamins, blood and skin cells ⁵, ⁶, ⁴. Proteins provide energy (calories) if necessary, the others are fat and carbohydrates. Proteins do everything from fighting infections to helping cells divide. Protein is also important for growth and development in children, teens, and pregnant women.

Excess or deficiency of protein can lead to disease, resulting in nervous system defects, metabolic problems, organ failure, and even death ¹. Clinical symptoms of inadequate intake of essential amino acids may include depression, anxiety, insomnia, fatigue, weakness, and growth stunting in the young. These symptoms are mostly caused by a lack of protein synthesis in the body because of the lack of essential amino acids ⁴. Kwashiorkor and marasmus are examples of more severe clinical disorders caused by malnutrition and inadequate intake of essential amino acids as a macronutrient ⁴.

High protein diets can promote weight loss via increased insulin sensitivity, fatty acid oxidation, appetite suppression, and feeling full. However, caution is necessary for people with diabetes who have gout because protein can elevate niacin levels, which may exacerbate gout-related symptoms.

The protein in your food is broken down into parts called amino acids during digestion. Your body needs a number of amino acids in large enough amounts to maintain good health. While there are hundreds of amino acids, humans use only 20 amino acids ¹, ⁴.

Amino acids are classified into three groups ¹:

1. Essential amino acids. Essential amino acids cannot be made by your body, and must be supplied by food. Essential amino acids do not need to be eaten at every meal. The balance over the whole day is more important. There are 9 essential amino acids:
   • Histidine
   • Isoleucine
   • Leucine
   • Lysine
   • Methionine
   • Phenylalanine
   • Threonine
   • Tryptophan
   • Valine
2. Nonessential amino acids. Nonessential amino acids are made by your body from essential amino acids or in the normal breakdown of proteins. There are 5 amino acids that are termed non-essential amino acids:
   • Alanine
   • Asparagine
   • Aspartic acid
   • Glutamic acid
   • Serine
3. Conditionally Essential amino acids. Conditionally Essential amino acids are needed in times of illness, stress, starvation or inborn errors of metabolism. A healthy body can make conditionally essential amino acids under normal physiologic conditions. There are 6 amino acids that are called conditionally essential amino acids:
   • Arginine
   • Cysteine
   • Glutamine
   • Glycine
   • Proline
   • Tyrosine

You get protein (amino acids) in your diet from animal and plant-based foods such as meat, fish, eggs, dairy products, nuts, and certain grains, beans, peas, and lentils ⁷. Proteins from meat and other animal products are complete proteins. This means they supply all of the amino acids your body can’t make on its own. Most plant proteins are incomplete. So you should eat different types of plant proteins every day to get all nine essential amino acids your body needs. For example, pairing protein sources like rice and beans, hummus, pita bread, or oatmeal topped with almond butter. Regarding volume, it may be necessary to eat more plant-based foods to get a similar amount of protein and amino acid profile provided by animal-based proteins ⁸.

The Dietary Guidelines for Americans recommend a variety of protein foods from both animal and plant sources in healthy dietary patterns ⁹. The Dietary Guidelines for Americans also recommend a variety of nutrient-dense protein foods from both plant (beans, peas, lentils, and cereal grains) and animal sources (lean meat, poultry, fish, eggs, as well as low-fat dairy products) to ensure adequate nutrient intake ⁹. You should try to include at least one protein-rich food with every meal. Eating foods high in protein can help you build strength and recover more quickly if you’ve been sick.

Protein foods include ¹⁰, ¹¹, ¹², ¹³:

• Animal-based protein foods: Red and white meat (pork, beef, chicken, turkey, duck), seafood (fish, shrimp, oysters, clams, and scallops), eggs, milk, yogurt, and cheese. Animal-based protein sources, such as meat and dairy products, contribute zinc, vitamin B12, vitamin D, calcium, phosphorus, and iron. Meat and poultry foods should be lean or low-fat, like 93% lean ground beef, pork loin, and skinless chicken breasts. Fish is nutritious, providing energy (calories), protein, selenium, zinc, iodine and vitamins A and D (some species only). Fish is also an excellent source of omega-3 fatty acids (good fats), which are well known for their health benefits and are essential for life. Eating fish regularly can reduce the risk of a range of diseases from childhood asthma to heart disease, cardiovascular diseases and prostate cancer. Choose seafood options that are higher in healthy fatty acids called omega-3s fatty acid and lower in methylmercury, such as salmon, anchovies, and trout. And stay away from processed meats or artificial (fake) meat.
• Plant-based protein foods: Nuts and nut spreads such as almond butter, peanut butter, soy nut butter, seeds (sunflower seeds), beans, peas, legumes, lentils, soy products, soy milk, and tofu. Plant protein foods, such as legumes (including soybeans and pulses), nuts, seeds, and cereal grains contribute to dietary fiber, potassium, folate, vitamin E, and magnesium. Peanuts and peanut butter are high in protein, folate, magnesium, and vitamin E. Legumes can also contribute significant non-heme iron to diets ¹⁰.

Good protein choices include:

• Soy protein
• Beans
• Nuts
• Fish
• Lean chicken with no skin
• Lean beef
• Pork
• Salmon
• Anchovies
• Trout
• Low-fat dairy products

It is important to get enough dietary protein. You need to eat protein every day, because your body doesn’t store it the way it stores fats or carbohydrates. Furthermore, protein foods provide nutrients important for maintaining your health and body. How much protein you need depends on your age, sex, height, weight, health, and level of physical activity. The amount can also depend on whether or not you are pregnant or breastfeeding. The good news is most Americans eat enough protein and some eat more than they need ¹⁴. In the US, about a one-third of protein comes from plant sources, which are primarily derived from grain foods ⁷.

Choosing animal-based sources can be beneficial, as they’re considered complete proteins, meaning they contain all 9 essential amino acids. Animal-based protein sources also contain vitamins and minerals such as vitamin B12 and iron. However, some animal proteins, such as processed meats and certain cuts of meat that are high in saturated fat, can affect your health negatively. It’s best to choose leaner protein sources and cut back on red meat (e.g., pork, beef, lamb) and processed meat (i.e., meat preserved by smoking, salting, curing or adding other preservatives). Because diets high in red meat and diets high in processed meat have been linked to increased risk of colorectal cancer. If you do choose to eat red meat, choose leaner sources. Look for sources that are low in saturated fat, are unprocessed, or are high in heart-healthy unsaturated fats and omega-3 fatty acids. Some good examples are:

• White-meat poultry, such as chicken or turkey breasts
• Fish, especially fatty fish like salmon, lake trout, mackerel, herring, sardines and tuna
• Pork tenderloin
• Lean or extra-lean cuts of beef such as sirloin or round cuts, greater than 93% lean ground beef
• Eggs and egg whites
• Non-fat/low-fat Greek yogurt, cottage cheese, milk

Remember that it’s still important to eat a balanced diet that includes all food groups and a variety of both plant and animal protein sources, in addition to plenty of fruits, vegetables and whole grains ¹⁵, ¹⁶. Although individual plant protein sources (e.g., beans, nuts and seeds) don’t contain all 9 essential amino acids, plant sources offer more fiber and a different variety of vitamins and minerals than animal sources of protein. And even though individual plants don’t contain all 9 essential amino acids on their own, when eaten in combination throughout the day, they do provide enough of the essential amino acids to meet your body’s needs. An ideal human diet would consist of both animal- and plant-source foods in appropriate amounts and proportions to ensure intake of sufficient quantity and quality of proteins, while consuming adequate dietary fiber ¹⁷.

The recommended protein intake is 0.8 to 1 gram per kilogram of body weight per day ¹⁸. For strength training athletes adequate protein intake should range between 1.2 and 1.7 grams of protein per kilogram of body weight per day or 0.5 to 0.8 grams per pound of body weight ¹⁹, ²⁰, ²¹, ²². Recently, the American Dietetic Association, and Dieticians of Canada recommended that endurance-training (moderate exercise) athletes and strength-training (intense exercise) athletes consume 1.3 (ranging from 1.2 to 1.4) and 1.6 (ranging from 1.2 to 1.7) g protein per kg body weight per day, respectively ²³. There is evidence that the inclusion of high-quality animal protein or combinations of high-quality plant-based proteins can stimulate muscle growth ²⁴. Recent data also indicate that adequate intake of protein at each meal of the day has an advantage over a large amount of protein in a single meal to support skeletal-muscle mass and function ²³.

Timing of protein or amino acids consumption is also important for muscle recovery after exercise. Skeletal muscle takes up nutrients (e.g., amino acids, glucose and fatty acids) from the blood circulation most efficiently within the first 30 to 60 minutes after an exercise program is completed, followed by great reductions several hours later ²⁵. Therefore, the response of muscle protein synthesis to exercise-induced growth is much greater when amino acids intake is initiated immediately after the end of exercise, as compared to 3 hour after the end of exercise ²⁶. The proportions and amounts of all amino acids in diets should be considered when specific essential amino acids are supplemented to subjects after exercise. For example, consuming individual branched-chain amino acids (BCAA) alone cannot enhance muscle protein synthesis when the availability of other amino acids is limited ²⁷. This is because protein synthesis requires all 20 different amino acids as the building blocks.

For healthy children ages 1 to 3, approximately 5 to 20% and children ages 4 to 18 approximately 10 to 30% of daily energy intake should come from protein. The daily recommended intake of protein for healthy adults is 10% to 35% of your daily energy intake based on the adequate amount needed for nitrogen equilibrium ²⁸. One gram of protein supplies 4 calories. Therefore, if you consume 2,000 calories per day, this would work out to be between 200 to 700 calories of protein per day, you could eat 100 grams of protein, or 400 calories from protein, which would supply 20% of your total daily calories.

The recommended daily intakes (RDIs) can also be calculated by your body weight. The Academy of Nutrition and Dietetics recommends that the average individual should consume 0.8 grams of protein per kilogram or 0.35 grams per pound of body weight per day for general health. So a person that weighs 75 kg (165 pounds) should consume an average of 60 grams of protein per day. Since there are approximately four calories per gram of protein, 60 grams of protein would result in the intake of 240 calories.

If you’re looking for ways to get more protein into your diet, here are some suggestions:

• Try a peanut butter sandwich. Remember to use natural peanut butter (or any other nut paste) with no added salt, sugar or other fillers.
• Low-fat cottage or ricotta cheese is high in protein and can go in your scrambled eggs, casserole, mashed potato or pasta dish. Or spread it on your toast in the morning.
• Nuts and seeds are fantastic in salads, with vegetables and served on top of curries. Try toasting some pine nuts or flaked almonds and putting them in your green salad.
• Beans are great in soups, casseroles, and pasta sauces. Try tipping a drained can of cannellini beans into your favorite vegetable soup recipe or casserole.
• A plate of hummus and freshly cut vegetable sticks as a snack or hummus spread on your sandwich will give you easy extra protein at lunchtime.
• Greek yogurt is a protein rich food that you can use throughout the day. Add some on your favorite breakfast cereal, put a spoonful on top of a bowl of pumpkin soup or serve it as dessert with some fresh fruit.
• Eggs are a versatile and easy option that can be enjoyed on their own or mixed in a variety of dishes.

Figure 1. Amino acid structure

Footnotes: Amino acids are the fundamental building blocks of proteins, essential for the structure, function, and regulation of biological systems. Amino acid basic structure has 4 components linked together with a central carbon atom called alpha carbon (α–carbon). All amino acids contain an amino group (-NH₂) and a carboxyl group (-COOH). In alpha-amino acids (α-amino acids), the two functional groups are bound to a central carbon atom known as the alpha carbon (α–carbon). At the alpha carbon is also a hydrogen atom (H) and a variable side chain, often referred to as the R-group (R), which varies with each amino acid and gives each amino acid its unique chemical properties. The ​​​R groups (R) may be: Hydrophobic, Hydrophilic, Charged R-groups: positive or negative charged and Special R-groups: conjugated with other molecules

[Source ²⁹ ]

Figure 2. Amino Acid Chart

Footnotes: All amino acids contain an amino group (-NH₂) and a carboxyl group (-COOH). In alpha-amino acids (α-amino acids), the two functional groups are bound to a central carbon atom known as the alpha carbon. At the alpha carbon is also a hydrogen atom and a variable side chain, often referred to as the R-group, which gives each amino acid its unique chemical properties. Nonpolar amino acids (hydrophobic amino acids) have R-groups that are mostly composed of hydrocarbons and are hydrophobic. Examples include glycine (Gly), alanine (Ala), valine (Val), leucine (Leu), isoleucine (Ile), proline (Pro), methionine (Met), and phenylalanine (Phe). Polar amino acids (uncharged amino acids) have R-groups that contain polar functional groups but do not ionize under physiological conditions. Examples include serine (Ser), threonine (Thr), cysteine (Cys), asparagine (Asn), and glutamine (Gln). Basic amino acids (positively charged amino acids) have R-groups that contain positively charged functional groups, which can form ionic bonds with negatively charged groups. Examples include lysine (Lys), arginine (Arg), and histidine (His). Often charged side chains appear at the protein surface to enable solubility in water. Neighboring side chains with positive and negative charges can form electrostatic contacts called salt bridges that maintain structures within a single protein or between interfacing proteins. Acidic amino acids (negatively charged amino acids) have R-groups that contain negatively charged functional groups, which can form ionic bonds with positively charged groups. Examples include aspartic acid (Asp) and glutamic acid (Glu). Some proteins use charged side chains to bind metals that are important for the proteins function.

[Source ³⁰ ]

Figure 3. Peptide bond

Footnote: Amino acids link together in a reaction known as peptide bond to form proteins.

[Source ³¹ ]

Figure 4. Protein structure

Footnotes: A protein is a chain of amino acids bound to one another via peptide bonds. Like a string of beads, these strings can twist and fold into a final protein shape. When someone eats protein, it breaks down into its amino acids. These amino acids are composed of a central carbon atom bonded to an amino group (-NH₂) or nitrogen-containing group and a carboxylic “acid” group (-COOH), hence the name “amino acid”. The carbon also has a single hydrogen atom and a side chain or “R-group,” unique to each amino acid. The exception to this is Proline, which is a ring structure.

[Source ³² ]

Figure 5. Protein structures

[Source ³³ ]

How much protein do I need?

How much protein you need depends on your age, sex, height, weight, health, and level of physical activity. The amount can also depend on whether or not you are pregnant or breastfeeding. The recommended protein intake is 0.8 to 1 gram per kilogram of body weight per day ¹⁸. For strength training athletes adequate protein intake should range between 1.2 and 1.7 grams of protein per kilogram of body weight per day or 0.5 to 0.8 grams per pound of body weight ¹⁹, ²⁰, ²¹, ²².

Some fad diets promote very high protein intakes of between 200 and 400 g per day. This is more than 5 times the amount recommended in the American dietary guidelines.

The protein recommendations in the American dietary guidelines provide enough protein to build and repair muscles, even for body builders and athletes.

There are some reports that long-term high protein intake above the Recommended Dietary Allowance (RDA) is unhealthy and may result in unnecessary metabolic strain on your kidneys, leading to impaired kidney function ³⁴. Another concern is that high protein diets increase loss of the mineral calcium, thereby increasing your risk for osteoporosis ³⁵. However, both of these concerns are unfounded as there is no substantive evidence that protein intakes in the ranges between 200 and 400 g per day, in conjunction with a balanced diet, will have adverse effects in healthy, exercising individuals.

In a 2014 study conducted in adults aged 50 to 65 who reported a high protein intake had a 75% increase in overall mortality and were 4 times more likely to die from cancer during the following 18 years than those in the low protein group ³⁶. The moderate-protein diet was associated with a 3-fold increase in cancer mortality compared to the low-protein diet. A high-protein diet was also associated with a 5-fold increase in diabetes mortality across all ages ³⁶. One limitation of that study, the researchers note, is that the participants’ protein intake was based on a single 24-hour dietary recall ³⁶. The study also didn’t examine the effects of specific types of plant- or animal-derived proteins, such as beef or fish ³⁶.

How to calculate your daily protein needs

Convert body weight in pounds to kilograms (round to the nearest 10th).
 Multiply weight in kilograms by the range that best fits your activity levels.

Let’s look at an example:

• Convert pounds into kilograms 150lbs / 2.2 = 68.2kg

The recommended protein intake is 0.8 to 1 gram per kilogram of body weight per day

• 68.2kg (0.8g grams of protein per kilogram) = 54.6g
• 68.2kg (1g grams of protein per kilogram) = 68.2g

For strength training athletes adequate protein intake should range between 1.2 and 1.7 grams of protein per kilogram of body weight per day.

• 68.2kg (1.2g grams of protein per kilogram) = 81.8g
• 68.2kg (1.7g grams of protein per kilogram) = 115.9g

Here are some practical protein equivalents in common foods. One ounce (30 grams) of most protein-rich foods contains 7 grams of protein. An ounce (30 grams) equals:

• 1 oz (30 g) of meat fish or poultry
• 1 large egg has six grams of protein
• ¼ cup (60 milliliters) tofu
• ½ cup (65 grams) cooked beans or lentils
• 1 cup of dry beans has about 16 grams of protein
• 1 cup of milk has eight grams of protein
• 1 cup of soy milk has about seven grams of protein

Low fat dairy is also a good source of protein. An eight ounce container of yogurt has about 11 grams of protein

Most Americans eat enough protein in their diet but need to select leaner varieties of meat and poultry. Americans may also need to increase the variety of protein foods selected and choose meats less often. However, if you are vegetarian or vegan, the advice to eat meat, poultry, and seafood does not apply to you. Vegetarian protein options include beans, peas, lentils, nuts, seeds, and soy products.

What counts as an ounce-equivalent in the protein foods group?

The following examples count as 1 ounce-equivalent from the protein foods group ⁶:

• 1 ounce of meat, poultry, or fish
• ¼ cup cooked beans
• 1 egg
• 1 tablespoon of peanut butter
• ½ ounce of nuts or seeds
• ¼ cup (about 2 ounces) of tofu
• 1 ounce tempeh, cooked

The table below lists amounts that count as 1 ounce-equivalent in the protein foods group towards your daily recommended amount.

Table 1. Daily protein foods general recommendations by age

Daily Protein Recommendation* in Ounce-Equivalents
Toddlers	12 to 23 months	2 ounce-equivalent
Children	2-3  yrs 4-8 yrs	2 to 4  ounce-equivalent 3 to  5½ ounce-equivalent
Girls	9-13 yrs 14-18 yrs	4 to 6  ounce-equivalent 5 to 6½ ounce-equivalent
Boys	9-13 yrs 14-18 yrs	5 to 6½ ounce-equivalent 5½ to 7 ounce-equivalent
Women	19-30 yrs 31-59  yrs 60+ yrs	5 to 6½ ounce-equivalent 5 to 6 ounce-equivalent 5 to 6 ounce-equivalent
Men	19-30 yrs 31-59  yrs 60+ yrs	6½ to 7 ounce-equivalent 6 to 7 ounce-equivalent 5½ to 6½ ounce-equivalent

How much protein do you need for optimal muscle maintenance?

The recommended protein intake is 0.8 to 1 gram per kilogram of body weight per day ¹⁸. For strength training athletes adequate protein intake should range between 1.2 and 1.7 grams of protein per kilogram of body weight per day or 0.5 to 0.8 grams per pound of body weight ¹⁹, ²⁰, ²¹, ²², ³⁷, ³⁸. That’s because your skeletal muscle is made up of 75 percent water and 20 percent protein, with the remainder from other materials including fat, glycogen, inorganic salts, and minerals ³⁹. Given the protein content of your skeletal muscle, it is not surprising resistance trained athletes emphasize the importance of dietary protein in their meal plans ⁴⁰. This is also reflected in the scientific literature with significant attention given to protein focused nutritional interventions to facilitate resistance training induced adaptations ⁴¹, including manipulation of total daily dietary protein intake ⁴², protein dosage per meal ⁴³, ⁴⁴, ⁴⁵, protein quality ⁴⁶ and protein distribution ⁴⁷.

Protein is also for maintaining muscle mass as you age. From around 50 years of age, humans begin to gradually lose skeletal muscle. This is known as sarcopenia and is common in older people. Loss of muscle mass is worsened by chronic illness, poor diet and inactivity.

Meeting the daily recommended protein intake may help you maintain muscle mass and strength. This is important for maintaining your ability to walk and reducing your risk of injury from falls.

To maintain muscle mass, it’s important for older people to eat protein ‘effectively’. This means consuming high-quality protein foods, such as lean meats.

Higher-protein diets have been shown to ⁴⁸, ⁴⁹, ³⁷, ³⁸:

1. Promote gains in muscle mass, especially when paired with resistance training;
2. Spare muscle mass loss during caloric restriction; and
3. Reduce the natural loss of muscle mass that accompanies aging.

Protein quality is also important to the gain and maintenance of muscle mass ⁵⁰. Protein quality is a function of protein digestibility, amino acid content, and the resulting amino acid availability to support metabolic function ⁵⁰. Whey protein is one of the highest-quality proteins given its amino acid content (high essential, branched-chain, and leucine amino acid content) and rapid digestibility. Consumption of whey protein has a strong ability to stimulate muscle protein synthesis ⁵⁰. In fact, whey protein has been found to stimulate muscle protein synthesis to a greater degree than other proteins such as casein and soy.

A recent meta-analysis suggested dietary protein supplementation enhances resistance training induced gains in muscle mass and strength, at least when dietary protein intake is suboptimal (<1.6 g per kg body weight daily) ⁵¹, resistance training alone provides a far greater stimulus than whey protein supplementation ⁴⁴.

How to calculate your daily protein needs:

Convert body weight in pounds to kilograms (round to the nearest 10th).
 Multiply weight in kilograms by the range that best fits your activity levels.

Let’s look at an example:

• Convert pounds into kilograms 150lbs / 2.2 = 68.2kg

The recommended protein intake is 0.8 to 1 gram per kilogram of body weight per day

• 68.2kg (0.8g grams of protein per kilogram) = 54.6g
• 68.2kg (1g grams of protein per kilogram) = 68.2g

For strength training athletes adequate protein intake should range between 1.2 and 1.7 grams of protein per kilogram of body weight per day.

• 68.2kg (1.2g grams of protein per kilogram) = 81.8g
• 68.2kg (1.7g grams of protein per kilogram) = 115.9g

Muscle mass is built when the net protein balance is positive: that is muscle protein synthesis exceeds muscle protein breakdown. Research shows muscle protein turnover is the greatest after working out. Additionally, it has been shown that muscle mass increases over time when resistance exercise (i.e. weight lifting, body weight exercises, etc) is combined with nutrient intake.

However, as you age, you need to increase your protein intake ¹⁹. Around 50 years of age, you need to increase the protein in your diets to 1 gram per kilogram of your body weight to maintain muscle mass ¹⁹. People that exercise regularly also need to eat more protein than the recommended daily intake ¹⁹.

Several studies performed by the group of Philip and others showed that protein supplementation did not further increase muscle strength among individuals who consumed adequate amounts of dietary protein ²², ⁵², ²⁰, ⁵³. However, with the aim of maximizing performance, individuals seeking to gain muscle mass are likely to consume more protein with the misconceived belief that large quantities of protein consumption might generate more muscle protein ⁵⁴.

To increase muscle mass in combination with physical activity, it is recommended that a person that lifts weights regularly or is training for a running or cycling event eat a range of 1.2 to 1.7 grams of protein per kilogram of body weight per day, or 0.5 to 0.8 grams per pound of body weight ¹⁹. Consequently, the same 75
kilogram individual should increase their protein intake to 75 grams (300 calories) to 128 grams (512 calories) in order to gain muscle mass. This level of intake can generally be met through diet alone and without additional protein and amino acid supplementation ¹⁹.

When should I consume protein?

The process of protein turnover is increased with resistance training and can remain elevated for up to 48 hours in people beginning a new resistance training program ¹⁹. Therefore it is important to provide enough energy including protein so there is a sufficient pool of amino acids available to repair and build new muscle. You do not want to exercise on an empty stomach. In fact, exercising in an unfed state leads to an increase in protein loss making it more difficult for your body to both repair and build muscle ¹⁹. Your body can only use approximately 20–40 g of protein per meal. For best results, eat around this much protein every 3 to 4 hours.

Research suggests there are several benefits to pre-exercise protein supplementation ¹⁹. Pre-exercise protein supplementation helps to improve body composition by increasing resting energy expenditure up to 48 hours after exercise ¹⁹. This is important because it suggests that pre-exercise protein ingestion will not only help increase lean muscle mass and strength, but will also simultaneously reduce fat mass ¹⁹. However, the most scientifically supported and most significant benefits of consuming protein prior to exercise may be improved recovery and hypertrophy. This is thought to occur because of improved amino acid delivery ¹⁹.

Make sure you have a healthy diet that meets the current protein intake recommendations and then use supplements to add anything else you might need. A good diet will not make a mediocre athlete into a champion, but poor food choices can turn a champion into a mediocre athlete. The International Olympic Committee (IOC) position stand is that “the use of supplements does not compensate for poor food choices and an inadequate diet”. Reinforcing this importance of food, researchers have found that athletes eating a diet rich in nitrates from vegetables (not supplements) for just 10 days were able to enhance their exercise performance, compared to when they were eating their usual diet ⁵⁵.

Getting too little protein or protein deficiency

Protein deficiency means not getting enough protein in your diet. Protein deficiency is rare in America, as the American diet generally includes far more protein than you actually need ¹⁴. However, protein deficiency may occur in people with special requirements, such as older people and people following strict vegetarian or vegan diets.

Symptoms of protein deficiency include:

• Wasting and shrinkage of muscle tissue
• Edema (build-up of fluids, particularly in the feet and ankles)
• Anemia (the blood’s inability to deliver sufficient oxygen to the cells, usually caused by dietary deficiencies such as lack of iron)
• Slow growth (in children).

Protein supplement

Protein supplementation has been shown to improve muscle building with regular exercise training. Protein supplementation should contain a high amount of the amino acid leucine, which is responsible for muscle protein synthesis. Whey protein is a great option for leucine. Eating less protein may not be enough to rebuild muscles, and eating more doesn’t usually give you more benefits. Furthermore, a combination of whey (a rapidly digested protein) with casein (a slow digested protein) seems to be an effective formula for skeletal-muscle protein synthesis after exercise ³.

Whey protein is beneficial in supporting muscle adaptations due to its rapid absorption rate in addition to casein that has a slower and more sustained rate of amino acid absorption over a few hours ¹⁹. Branched chain amino acids are similarly beneficial and have been shown to aid in recovery from exercise with respect to not only protein synthesis but also aiding in replacing your muscle glycogen and delaying fatigue associated with exercise.

Protein supplementation after exercise may have a more profound impact on skeletal muscle growth. Several studies have demonstrated that protein ingestion following an acute bout of resistance training stimulates muscle protein synthesis for up to three hours ¹⁹. In contrast, failing to eat after exercise may limit protein synthesis and therefore limit potential progress in lean muscle tissue development. Research actually suggests there may be an “anabolic window” such that protein intake within an hour of exercise has the greatest influence on resistance training adaptations ¹⁹.

Generally, naturally occurring animal proteins contain 2:1:1 ratio of leucine, isoleucine and valine. These proteins have been identified as providing optimal support of muscle adaptations with exercise training. In order to meet the recommended RDA a consumption of approximately 45 mg/kg/day of leucine and 22.5 mg/kg/day of isoleucine and valine is suggested ¹⁹.

Protein powder

When people think of protein supplement, they might think of powder mixed with water in a shaker bottle. However, as we mentioned above, protein comes from many different sources and also does more for the body than just repair muscle. Protein is made up of amino acids and is required for nearly everything that your body does to function properly. The protein in your food is broken down into parts called amino acids during digestion. Amino acids are referred to as the building blocks of protein – imagine the structure of a brick wall. One brick by itself only has so much strength, but many stacked on top of one another can create an entire wall, build houses or even buildings. The same goes for amino acids – individually, they’re not as “effective” – but when strung together to form an entire protein, they can ultimately help build and repair muscle along with assisting with their many other “jobs” in the body. High protein diets can promote weight loss via increased insulin sensitivity, fatty acid oxidation, appetite suppression, and feeling full. However, caution is necessary for people with diabetes who have gout because protein can elevate niacin levels, which may exacerbate gout-related symptoms.

Your body needs a number of amino acids in large enough amounts to maintain good health. While there are hundreds of amino acids, humans use only 20 amino acids ¹, ⁴.

Amino acids are classified into three groups ¹:

1. Essential amino acids. Essential amino acids cannot be made by your body, and must be supplied by food. Essential amino acids do not need to be eaten at every meal. The balance over the whole day is more important. There are 9 essential amino acids:
   • Histidine
   • Isoleucine
   • Leucine
   • Lysine
   • Methionine
   • Phenylalanine
   • Threonine
   • Tryptophan
   • Valine
2. Nonessential amino acids. Nonessential amino acids are made by your body from essential amino acids or in the normal breakdown of proteins. There are 5 amino acids that are termed non-essential amino acids:
   • Alanine
   • Asparagine
   • Aspartic acid
   • Glutamic acid
   • Serine
3. Conditionally Essential amino acids. Conditionally Essential amino acids are needed in times of illness, stress, starvation or inborn errors of metabolism. A healthy body can make conditionally essential amino acids under normal physiologic conditions. There are 6 amino acids that are called conditionally essential amino acids:
   • Arginine
   • Cysteine
   • Glutamine
   • Glycine
   • Proline
   • Tyrosine

There are 3 main types of protein powders:

1. Whey. Whey is the liquid remaining after milk has been curdled and strained. It is very fast absorbing and is generally the type of protein that is recommended after exercise.
2. Casein. Casein protein is also a by-product of milk production and is a slower digesting protein. This protein is generally best to consume at night or as a snack.
3. Plant protein powders. Plant protein powders are generally a combination of protein derived from wheat, pea, hemp, or soy products. Plant proteins generally contain a combination of various protein sources to include all the essential amino acids needed to build new tissue.

Protein shakes, powders and supplements are unnecessary for most Americans’ health needs. According to the most recent national nutrition survey, 99% of Americans get enough protein through the food they eat ⁷. Any protein you eat on top of what your body needs will either be excreted from your body as waste, or stored as weight gain. The best way for you to get the protein you need is to eat a wide variety of protein-rich foods as outlined in the American dietary guidelines, as part of a balanced diet. But if you are still interested in using protein shakes, powders and supplements, talk to your doctor ⁹. Protein powders especially whey or casein protein powders are complete protein sources. Furthermore, they are in an elemental form so your body will absorb and utilize those proteins quickly. This makes protein powders an excellent source of protein in the diet for fitness enthusiasts or athletes alike. However, unlike protein from food source, when it comes to protein powders, it’s important to be aware of additional ingredients that can be placed in them like heavy metals, artificial sweeteners, fillers, and sugar alcohols.

Cadmium (Cd), Arsenic (As), Mercury (Hg), and lead (Pb) are among the 4 most common heavy metals found in protein powders ⁵⁶. In 2010, the US Consumer Reports measured heavy metal concentrations in 15 commercially available protein powder supplements, and reported that all of the examined products contained “detectable concentrations” of at least one heavy metal ⁵⁷. In a separate evaluation in 2018, the Clean Label Project tested 133 protein powder supplements, and found that all of the tested products similarly contained “detectable concentrations” of heavy metals ⁵⁸. Specifically, the Clean Label Project reported that 70 % and 74 % of the test products contained “measurable levels” of lead (Pb) and xadmium (Cd), respectively ⁵⁸. These studies are cited by the media as evidence for possible adverse health effects following consumption of protein powder supplements.

When ingested in sufficient quantities, cadmium (Cd), arsenic (As), mercury (Hg), and lead (Pb) have been associated with adverse human health effects, potentially including cancers, nerve damage, kidney damage and fertitlity issues ⁵⁹, ⁶⁰, ⁶¹, ⁶², ⁶³, ⁶⁴, ⁶⁵. For example, chronic exposure to cadmium (Cd) is associated with kidney disease, thyroid disruption, and weakened bones, while chronic exposure to arsenic (As) is associated with skin lesions and cancers ⁶⁶, ⁶⁷, ⁶⁸, ⁶⁹. Additionally, high doses of ingested lead (Pb) compete with calcium in your body, affecting neurotransmitter release and heme synthesis, which may result in nervous, blood, reproductive, and kidney problems ⁶¹, ⁷⁰, ⁷¹. Sufficient mercury (Hg) exposure can elicit neurological, motor, kidney, cardiovascular, immune and reproductive dysfunction ⁷².

To add flavor without adding extra sugar or calories, sugar alcohols or artificial sweeteners are commonly used in protein powders. Some common sweeteners include sucralose, aspartame, erythritol, sorbitol, and xylitol. There is some debate concerning the effects of artificial sweeteners on the gut microbiome ⁷³, ⁷⁴, ⁷⁵, ⁷⁶, ⁷⁷, ⁷⁸. Some studies have shown that in mice, artificial sweeteners had negative effects on glucose metabolism which lead to weight gain. In human studies, there has been evidence to show that artificial sweeteners disrupt the learning process associated with recognizing “real sugar” and decreased hormone signaling responsible for feelings of fullness which lead to weight gain. While the results are varied and warrant more research, excessive consumption of artificial sweeteners does seem to impact the bacteria within the gut ⁷³, ⁷⁴, ⁷⁵, ⁷⁶, ⁷⁷, ⁷⁸.

In general, people who exercise vigorously or are trying to put on muscle mass do not need to consume protein shakes, powders and supplements. Protein shakes, powders and supplements do not lead to increased muscle mass ⁷⁹, ⁸⁰, ⁸¹, ⁸², ⁸³, ⁸⁴. It’s the stimulation of muscle tissue through weightlifting, resistance training (to strengthen muscles and stabilize joints to support more-efficient movement) and proper nutrition and not extra dietary protein, which leads to muscle growth. Studies show that weight-trainers who do not eat extra protein (either in food or protein powders) still gain muscle at the same rate as weight-trainers who supplement their diets with protein. A sedentary lifestyle has a profound negative effect on skeletal muscle. For example, a 7-day bed rest in young healthy males can decrease leg muscle mass by 3% and muscle oxygen consumption by 4% ⁸⁵. Much evidence shows that moderate exercise is beneficial for improving skeletal muscle mass as well as muscle and whole-body health, while reducing the risk of metabolic syndrome ²⁵.

Strength training or muscle-strengthening exercise is a key component of overall health and fitness for everyone. Strength training or muscle-strengthening exercise can reduce your body fat, increase lean muscle mass and burn calories more efficiently. Strength training will make you stronger, leaner and healthier.

Strength training involves lifting free weights, using stationary weight machines, resistance bands, or your own body weight such as push-ups, pull-ups and squats to make your muscles stronger. Strength training classes that incorporate some or all of the above activities will improve your balance and prevent falls.

Strength training may help you:

• build and maintain strong muscles as you get older
• continue to perform activities of daily living, such as carrying groceries or moving furniture
• keep your bones strong, which may help prevent osteoporosis and fractures.

As you incorporate strength training exercises into your fitness routine, you may notice improvement in your strength over time. As your muscle mass increases, you’ll likely be able to lift weight more easily and for longer periods of time. If you keep it up, you can continue to increase your strength, even if you’re not in shape when you begin.

Strength-training tips:

• Aim for at least 2 days per week of strengthen-training activities.
• Try to perform each exercise 8 to 12 times. If that’s too hard, the weight you are lifting is too heavy. If it’s too easy, your weight is too light.
• Try to exercise all the major muscle groups. These groups include the muscles of your legs, hips, chest, back, abdomen, shoulders, and arms.
• Don’t work the same muscles 2 days in a row. Your muscles need time to recover.

If you are just starting out, using a weightlifting machine may be safer than dumbbells. As you get fit, you may want to add free-weight exercises with dumbbells.

You do not need a weight bench or large dumbbells to do strength training at home. You can use a pair of hand weights to do bicep curls. You can also use your own body weight: for example, push-ups, pull-ups and squats.

Proper form is very important when lifting weights. You may hurt yourself if you don’t lift weights properly. You may want to schedule a session with a certified fitness professional to learn which exercises to do and how to do them safely.

If you decide to buy a home gym, check how much weight it can support to make sure it is safe for you.

Whey Protein Powder

Whey is the liquid remaining after milk has been curdled and strained to make cheese or casein production ⁸⁶, ⁸⁷, ⁸⁸, ⁸⁹. Only 20% of milk is made up of whey. Other components of milk are lactose, protein, fat, and water. In general, liquid whey obtained from cheese-making has 94.3% water, and 50% total solids, from which 4.3% lactose, 0.8% whey proteins, 0.5% minerals, and 0.1% fat can be extracted ⁹⁰. A large cheese factory may create more than 1 million liters of whey every day. Nine liters of whey are produced as the residue of each kilogram of cheese produced ⁸⁷.

Whey can be divided into 2 types ⁹¹:

1. Sweet whey, which is a by-product during the production of cheddar cheese or other types of cheese coagulated with rennet at pH 6–7.
2. Acid whey, which is a by-product of the production of fresh and cream cheese, Greek yogurt, and caseinates by coagulating casein at pH < 5.

Whey protein can be prepared through the clarification, ultrafiltration, nanofiltration and drying process of whey ⁹².

Whey protein contains a range of proteins, including 50–60% beta-lactoglobulin (β-lactoglobulin), 15–25% alpha-lactalbumin (α-lactalbumin), bovine serum albumin, 10% immunoglobulins (IGs), < 3% bovine lactoferrin (BLF), ≥ 15% glycomacropeptide, and bovine lactoperoxidase (LP) ⁹³, ⁹⁴, ⁸⁷. When whey is not consumed by humans, it is supplied to pigs and various other cattle, used as a fertilizer, or discarded ⁹⁵.

Whey protein biological components like beta-lactoglobulin (β-lactoglobulin), glycomacropeptide, alpha-lactalbumin (α-lactalbumin), lactoferrin, and immunoglobulins (IGs) exhibit a range of immune-boosting characteristics ⁹⁶. Whey has anti-cancer, anti-inflammatory, anti-high blood pressure, lipid lowering, antiviral, and antibacterial properties in addition to chelating ⁹⁷. The intracellular metabolism of cysteine, an amino acid, to glutathione, a powerful intracellular antioxidant, is the main mechanism through which whey is believed to provide its benefits ⁸⁷. Numerous clinical studies have shown the use of whey in the resistance of diseases like cancer, hepatitis B, osteoporosis, HIV, cardiovascular disease, and as an antibacterial agent ⁹⁸.

All the essential amino acids such as histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine are present in high-quality proteins known as bovine whey proteins ⁸⁷. These proteins also contain bioactive peptides, which facilitate easy digestion ⁹⁰.

Whey protein is very fast absorbing and is generally the type of protein that is recommended after exercise ⁹⁹, ¹⁰⁰, ¹⁰¹, ¹⁰².

Whey protein can be distinguished into whey protein concentrate (WPC), whey protein isolate (WPI), and whey protein hydrolysates (WPH) according to the difference in components and processing procedures ¹⁰³.

Ultrafiltration is employed to separate lactose and whey protein, resulting in whey protein concentrate (WPC) with protein content ranging from 20 to 80% and have more carbohydrates and fat. To further increase protein content and eliminate any carbohydrate or fat sources, microfiltration is utilized to obtain whey protein isolate (WPI) ¹⁰⁴. Ideally, whey protein isolate (WPI) will digest and absorb faster than a whey protein concentrate (WPC), but both are equal in terms of protein quality.

Whey is a soluble protein that empties rapidly from your stomach, therefore becoming rapidly assimilated into your body (whey protein isolates (WPI) can enter your blood within 15 to 20-minutes after ingestion on an empty stomach). Whey is mother nature’s ‘fastest protein’ (whey protein isolate [WPI] and whey protein hydrolysates [WPH]) that supports muscle protein synthesis in the immediate hours following a workout. Whey protein is a richer source of branched chain amino acids (BCAAs) and glutamine, containing approximately 24 to 25% more leucine than casein. Leucine is considered the all-important essential amino acid which acts as the engine to drive muscle protein synthesis.

Since whey is a by-product of milk, you can source it naturally from dairy products. Consuming whey protein is extremely beneficial because whey is a complete protein — meaning it contains all the amino acids necessary for muscle growth. In fact, in terms of protein quality, milk proteins have the highest digestibility score. However, whey protein contains a myriad of additional benefits aside from enhancing muscle growth. Studies have shown that consumption of whey can also improve sleep quality and enhance immune system responses.

Several studies have evaluated the effects of whey protein on training and performance and have found that consumption of whey in doses of 20-40g/day or more over 8-12 weeks showed increases in lean body mass, strength, and decreases in fat mass.

So, what does this mean if you’re trying to build muscle? Whey is a great, complete source of protein that will offer the most benefit if consumed every 3-4 hours (if not consuming additional sources of protein via food), or within 2 hours after exercise in doses of 20-40g.

Figure 6. Physiological effect of whey proteins inside the human body

[Source ⁸⁷ ]

Table 2. Therapeutic applications of whey protein in humans

Whey components	Whey protein (%)	Benefits
Beta-lactoglobulin	50 to 55	Source of branched-chain amino acids (BCAAs) and essential amino acids
Alpha-lactalbumin	20 to 25	Sources of branched-chain amino acids (BCAAs) and essential amino acids
Immunoglobulins	10 to 15	Immune modulating benefits
Lactoferrin	1 to 2	Antibacterial, antiviral, antifungal, and antioxidant properties encourage the development of necessary microorganisms
Lactoperoxidase	0.5	Inhibits the bacterial growth
Bovine serum	5 to 10	A source of vital amino acids hefty protein
Glycomacropeptide	10 to 15	Branched-chain amino acid source

[Source ⁸⁷ ]

Table 3. Amino acid content of various milk

Amino acids (g/100 g)	Cow milk	Goat milk	Buffalo milk
Aspartic acid	7.8	7.4	7.13
Serine	4.8	7.4	7.13
Threonine	4.5	5.7	5.7
Glutamic acid	23.2	19.3	21.4
Proline	9.6	14.6	12
Cystine	0.6	0.6	0.58
Glycine	1.8	2.1	1.9
Alanine	3	3.5	3.03
Valine	4.8	5.4	6.7
Methionine	1.8	3.5	0.9
Isoleucine	4.5	7	5.7
Leucine	8.5	8.2	9.5
Tyrosine	4.3	4.8	3.8
Phenylalanine	4.8	6	4.7
Histidine	3	5	2.7
Lysine	8	8	7.3

[Source ⁸⁷ ]

Casein protein

Casein is a milk protein, representing 75 to 80% (w/w) of all milk proteins present in milk, that’s sometimes found in non-dairy products such as soymilk, soy cheese and non-dairy creamer ¹⁰⁵. Casein protein component of milk is made up of four casein protein families proteins (κ-, β-, αS1-, and αS2-caseins) that have evolved in different mammalian species to maintain specialized roles in milk and their primary function is the provision of nutrients and minerals, especially calcium, to offspring while maintaining fluidity in mammary glands ¹⁰⁵, ¹⁰⁶.

A1 β-casein milk also called A1 milk is the most abundant milk, it is obtained from cows varieties, such as like Holstein Friesian and Jersey, while A2 β-casein milk also called A2 milk is mostly obtained from cows, such as Gir and Sahiwal, and milk from camels and goats ¹⁰⁷, ¹⁰⁸. Compared to A2 milk, A1 milk is relatively cheaper and easier to find. Recently, there has been a difference of opinion about the health effects of the A1 milk type ¹⁰⁹, ¹¹⁰, ¹¹¹. The digestion of regular cow’s milk, which includes A1 β-casein, can cause lactose intolerance and potential health problems mainly linked to its A1 β-casein and its derived peptide BCM-7 (Beta-casomorphine-7) which is derived from the A1 β-casein digestion of A1 milk, which is not present in A2 milk ¹¹². Moreover, BCM-7 (Beta-casomorphine-7) peptide formed during the digestion of A1 milk has been linked with several undesirable health effects from lactose intolerance to diabetes ¹¹³, ¹¹⁴, ¹¹⁵, ¹¹⁶. BCM-7 (Beta-casomorphine-7) morphine-like small peptide cannot be digested by human-associated enzymes, which causes indigestion problems. Several studies including epidemiological and clinical research have supported that the BCM-7 (Beta-casomorphine-7) is a risk for diseases such as gastrointestinal discomfort, type 1 diabetes, ischemic heart, and, neurological diseases ¹¹⁷, ¹¹⁸, ¹¹⁹, ¹²⁰, ¹²¹. Unfortunately, there are many conflicting reports on this subject in the scientific literature. The numerous studies and reports that have appeared in recent years do not provide a definitive answer of whether milk containing the A1 variant of β-casein has a negative effect on the human body, and whether there are grounds for avoiding the A1 milk ¹²², ¹²³, ¹²⁴. Furthermore, the report of the European Food Safety Authority “Scientific Report—Review of the potential health impact of β-casomorphins and related peptides” has not supported the hypothesis of the causal relationship between BCM-7 (Beta-casomorphine-7) exposure and the cause of human diseases, it also does not resolve the credibility hypothesis of the negative impact of the A1 β-casein variant, arguing that there is insufficient evidence and suggests further research in this field ¹²⁵. In summary, although the hypothesis on the influence of the A1 β-casein milk in A1 milk on human health was expressed almost 20 years ago, it still lacks conclusive evidence for its confirmation.

A1 β-casein in A1 milk is formed as a result of a point mutation in the position of 67th in the amino acid sequence A2 β-casein by changing proline to histidine. Therefore, this mutated form of β-casein in regular milk cannot easily be digested by the human-associated digestion enzymes ¹²⁶.

Because of the presumed undesirable health effects from lactose intolerance to diabetes of regular A1 milk and A1 milk based products have been excluded from the sports diet even though they benefit athlete health in several ways. The lack of cow’s milk in the diet of athletes means that they miss out on essential nutrients including protein, vitamin D, calcium, and potassium for their performance ¹²⁷, ¹⁰⁹. An alternative for athletes who have gut discomfort or other health problems due to the consumption of regular milk is A2 milk, which lacks A1 β-casein and related BCM-7 (Beta-casomorphine-7) protein, is considered to be a promising alternative to regular A1 milk for athletes who cannot consume it ¹²⁸, ¹²⁹, ¹³⁰.

Casein represents a group of insoluble proteins that form a gel (clot) in your stomach when it mixes with stomach acids (much like milk curdles when bacteria feast on milk sugars and release acids) – this slows gastric emptying significantly providing your body with a true ‘slow protein’ ¹³¹, ¹³². This provides a sustained (slow) release of amino acids into your blood which can last several hours and prolong muscle protein synthesis long after the completion of a workout. Casein is a good source of branched chain amino acids (BCAAs) and glutamine, both of which are believed to contribute positively to muscle protein synthesis and muscle recovery.

Figure 7. Casein molecular structure

Footnote: Caseins are single-chain polypeptides differing in length and amino acid sequence.

[Source ¹³³ ]

Collagen protein

Collagen belong to the family of fibrous or fiber-forming proteins that self-assemble into fibrils that define their mechanical properties and biological functions ¹³⁴. Collagen consists of protein fibrils wound in a strong triple helical structure. Collagen accounts for 30% of your body’s protein. Collagen is the main protein in many structural supportive connective tissues in your body such as skin, bones, ligaments, tendons, cartilage and muscle. Collagen is also found in your organs, blood vessels and intestinal lining. Collagen constitutes at least 70% of the dry weight of human skin.

More than 28 different types of collagen have been identified, but nearly 90% of all collagen in the human body comes from types 1 (I) to 3 (III). They differ by how the molecules are assembled, the cell components that are added and where the collagen is used in your body. All collagen fibrils have at least one triple helix structure.

The main 5 types of collagen and what they do are:

• Collagen type 1. Collagen type 1 makes up 90% of your body’s collagen. Collagen type 1 is densely packed and used to provide structure to your skin, bones, tendons and ligaments. Collagen type 1 is the major form of collagen found in the dermis (the middle layer of the skin, located beneath the epidermis), providing tensile strength in your skin.
• Collagen type 2. Collagen type 2 is found in elastic cartilage, which provides joint support.
• Collagen type 3. Collagen type 3 is found in muscles, arteries and organs. Collagen type 3 is also the main dermal collagen particularly in fetal skin.
• Collagen type 4. Collagen type 4 is found in the basement membrane zone of your skin.
• Collagen type 5. Collagen type 5 is found in the cornea of your eyes, some layers of skin, hair and tissue of the placenta.
• Collagen type 7. Collagen type 7 is also found in the basement membrane zone of your skin.

Collagen’s main role is to provide structure, strength and support throughout your body.

Collagen’s specific roles include:

• Helping fibroblasts form in your dermis (middle skin layer), which helps new cells grow.
• Playing a role in replacing dead skin cells.
• Providing a protective covering for organs.
• Giving structure, strength and elasticity to your skin.
• Helping your blood to clot.

Collagen deficiency can’t be measured with a blood test — but there are signs that your collagen level is decreasing. These signs and symptoms include:

• Skin that’s wrinkled, crepey or sagging.
• Hallowing in and around your eyes and face.
• Shrinking, weakening muscles and muscle aches.
• Stiffer, less flexible tendons and ligaments.
• Joint pain or osteoarthritis due to worn cartilage.
• Loss of mobility due to joint damage or stiffness.
• Gut problems due to thinning of the lining of your digestive tract.
• Problems with blood flow.

Collagen is formed in the human body by “assembling” collagen fibrils from 3 amino acids: proline, glycine, and hydroxyproline. These amino acids group together to form protein fibrils in a triple helix structure. These fibrils are then bundled into larger groups, much like muscle tissue, to make collagen fibers. As such, collagen has a cable-like structure in that it is comprised of many smaller bundles of proteins that are bundled together, which gives it much of its physical properties, including great tensile strength.

Collagen is synthesized in your skin by dermal fibroblasts, linking amino acids into a sequence of either glycine-proline-X or glycine-X-hydroxyproline where X can be any other amino acid. Every third amino acid in collagen is glycine and 20% are either proline or hydroxyproline. Glycine is the smallest amino acid, enabling the protein alpha chain to form a strong tight helical configuration. Hydroxylase enzymes add hydroxyl groups to proline and lysine using cofactor vitamin C. Hydroxyproline is unique to collagen. Glucose and galactose molecules are attached to selected lysine hydroxyl groups in a process called glycosylation. Three alpha helix chains coil upon each other into a triple helical structure. Outside the fibroblast, this propeptide collagen is trimmed by collagen peptidases to form a shortened tropocollagen molecule. In the final step, a copper-dependent enzyme, lysyl oxidase, facilitates the formation of stable crosslinks between lysine and hydroxylysine on separate tropocollagen molecules to give tensile strength to the collagen fibril.

Collagen in your body is continuously turned over. Collagen fibrils break down in response to oxidative cell damage and in the course of normal cellular metabolism involving the enzyme collagenase. A loss of balance between production and destruction of collagen results in reduced tensile strength and formation of skin wrinkles. Collagen degradation is accelerated by poor diet and excessive sun exposure. Nutritional deficiencies, such as scurvy, and genetic mutations, as in Ehlers-Danlos syndrome and osteogenesis imperfecta, result in construction errors in collagen.

Foods rich in collagen include bones, red meats (eg, lamb, beef, pork), and white meats (eg, poultry, fish, shellfish). Egg white, marine algae, and spirulina are also sources of collagen. Collagen lacks the essential amino acid tryptophan, so other protein sources such as beans and legumes are required for optimal health.

Proline is found in mushrooms, cabbage, asparagus, peanuts, wheat, fish, egg whites and meat. Glycine is found in red meats, turkey, chicken and pork skin, peanuts and granola.

Your body also needs the proper amount of vitamin C, zinc, copper and manganese to make the collagen triple helix. Vitamin C is a cofactor (a compound that is essential for the activity of an enzyme) essential for the synthesis of collagen. Fresh fruit and vegetables including citrus fruit, berries, kiwifruit, and beetroot, are rich sources of vitamin C.

Minerals including copper are also important in collagen production. Natural food sources of copper include shellfish, liver, lobster, oysters, shiitake mushrooms, nuts such as cashews, grains and seeds, fruit and vegetables including avocado, chickpeas, sweet potatoes, mushrooms, tofu and dark chocolate.

Zinc is found in oysters, red meat, poultry, pork, beans, chickpeas, nuts, broccoli, green leafy vegetables, whole grains and milk products.

Nutrients such as vitamins and minerals are best absorbed from fresh food sources compared to manufactured foods or supplements. Protein-deficient diets may benefit from collagen supplements.

Ingested collagen-rich foods are broken down to 2 to 3 amino acid oligopeptides (collagen hydrosylates) in your gut. Oligopeptides and single amino acids are easily absorbed from the large intestine into the bloodstream, from where they can be used to construct any required protein. Although the amino acid hydroxyproline is unique to collagen, it may be used to make collagen in any connective tissue, not just the skin.

While you can make the amino acids necessary to produce more collagen from other foods in your diet, consuming dietary collagen appears to be far more effective for replacing collagen than making collagen from other sources. The reason for this is that not only does eating dietary collagen provide more of the amino acids necessary when you consume collagen. It also tells specific cells in your skin to make more collagen. This has been shown to work in humans when sufficiently large quantities of collagen supplements are consumed (around 15 grams). Collagen supplements have been studied over the last several decades, and there are two main areas where there is good evidence to support collagen supplementation: skin and joint pain.

Collagen peptides are small pieces of animal collagen. Collagen can’t be absorbed in a whole form. It has to be broken down into smaller peptides or amino acids. Oral collagen supplements come in the form of pills and powders. They usually contain two or three amino acids. They are sold as collagen peptides or hydrolyzed collagen. Collagen peptides are made by breaking down whole collagen proteins into smaller pieces. Collagen peptides are absorbed through your gastrointestinal tract. When taken by mouth, collagen peptides seem to build up in your skin and cartilage. This might help improve some skin and joint conditions.

Collagen peptides are used for dry skin, aging skin and osteoarthritis. They are also used for osteoporosis, brittle nails, muscle strength, and many other purposes, but there is no good scientific evidence to support most of these uses.

• Aging skin. Skin aging is associated with a progressive reduction in collagen production and increased collagen breakdown. The three-dimensional spatial arrangement of collagen fibrils seen in young skin progressively becomes two-dimensional and the collagen bundles thin and become fragmented and clumped as the skin ages. These changes are accelerated by external factors including ultraviolet (UV) light, pollution, smoking and poor nutrition, resulting in skin dryness and wrinkling. Taking collagen peptides by mouth seems to improve skin hydration and skin elasticity in older people. It might also help reduce wrinkles, but it’s not clear if it helps enough to be noticeable.
• Dry skin. Taking collagen peptides by mouth seems to improve skin hydration and skin elasticity in people with dry skin.
• Pain associated with osteoarthritis. Collagen is one of the primary proteins in your joint connective tissue and another similar protein called elastin. Loss of collagen is one common reason for joint pain in some people. As such, it has been hypothesized that supplementation with collagen might be able to improve joint pain. The overall evidence from several randomized trials appear to be low, so making blanket recommendations for collagen supplementation in the treatment of osteoarthritis does not appear to be prudent at this time.
• Muscle strength. Taking collagen peptides by mouth does not seem to improve leg muscle strength. However, collagen peptides may improve hand-grip strength in the elderly.

There is interest in using collagen peptides for a number of other purposes, but there isn’t enough reliable information to say whether it might be helpful.

Collagen peptides have most often been used by adults in doses of 2.5 to 10 grams daily for up to 6 months. Speak with your doctor to find out what dose might be best for your specific condition.

Based on the scientific literature, there is no universally accepted time frame for how long it takes for collagen supplementation to show efficacy. However, most studies show benefits on outcome measures between 4-8 weeks, suggesting that a 1 to 2 months time frame appears to be a rough time frame for collagen supplements to show benefits.

Figure 8. Collagen structures

Footnotes: Collagens molecular structures. (a) Schematic representation of the most abundant collagen Pro-Hyp-Gly and Pro-Lys-Gly triplets. (b) Crystal structure of a collagen model (Gly-Pro-Hyp)10 single chain helix. (c) The collagen triple helix of the (Pro-Pro-Gly)10 model. Crystal structures are depicted in colored ball-and-stick representations.

[Source ¹³⁴ ]

Is collagen peptide safe?

When taken by mouth collagen peptides are possibly safe. Collagen peptides have been safely used in doses up to 10 grams daily for up to 6 months. Side effects are rare.

Collagen supplements in moderate doses (<30 grams per day) appear to be safe for humans. The Lethal Dose 50 (LD50) is an estimate of the amount of a substance that will kill half of a group of test animals when administered under controlled conditions. LD50 for oral collagen supplements in rodents is around 5 grams per kg, which would equate to about 350 grams a day for a 70 kg human being.

Muscle fibers

Muscle fibers are single muscle cells that help your body perform a specific physical function ¹³⁵. Like muscles themselves, not all muscle fibers are the same. There are 7 primary types of skeletal muscle fibers, including fast-twitch and slow-twitch. They each have different functions that are important to understand when it comes to movement and exercise programming.

Most experts agree that the distribution of muscle fiber types depend on the primary function of the muscle in question, as well as:

• Your Activity level. Your activity level and the types of activities that you do can affect how much you have of each muscle fiber type. For example, endurance athletes usually have a higher proportion of slow-twitch muscle fibers. And strength or power athletes usually have a higher amount of fast-twitch muscle fibers. But the exact proportion of each muscle fiber type can range from 15 to 85% of one type or the other, and the distribution also highly depends on the muscle. There’s also a theory that people who genetically have a higher percentage of slow-twitch fibers might be drawn to endurance activities, and people with more fast-twitch are drawn to power-based activities ¹³⁶.
• Your Age. Muscle fiber type is also heavily influenced by the aging process. The percentage of type 2 fast-twitch muscle fibers tend to decline with age. People usually reach peak muscle mass by the age of 30, which means they have a higher percentage of type 2 fast-twitch muscle fibers. Women experience a rapid decline in muscle mass post-menopause. Men have a more gradual decline in muscle mass during and after their 40s. That means that as most people age, they have a higher number of slow-twitch type 1 muscle fibers. However, humans still need to have some muscle strength as they age, which is why most experts recommend that older people continue to do strength training exercises ¹³⁷.
• Your Genetics.

Table 4. Muscle fiber types

Characteristic	Slow-Twitch Type 1	Fast-Twitch Type 2A	Fast-Twitch Type 2X or 2B
Activities	Marathons, distance running, swimming, cycling, power walking, endurance training	Powerlifting, sprinting, jumping, strength and agility training	Powerlifting, sprinting, jumping, strength and agility training
Muscle Fiber Size	Small	Large	Large
Force Production	Low	High	Very high
Resistance to Fatigue	Slow	Quick	Very quick
Contraction Speed	Slow	Quick	Very quick
Mitochondria	High	Medium	Low
Capillaries	High	Medium	Low
Myoglobin	High	Medium	Low
ATPase Level	Low	Medium	High
Oxidative Capacity	High	Medium	Low

Footnotes: *ATP (adenosine triphosphate) is the body’s energy currency. ATP provides energy for your muscle cell to contract. Type 2 muscle fibers have more readily available ATP. Type 1 fibers rely on aerobic respiration (oxygen delivery) to produce ATP in the muscle cells.

** Oxidative capacity refers to how much oxygen a gram of muscle uses in an hour.

[Source ¹³⁸ ]

Slow-Twitch muscle fibers

Slow-twitch muscle fibers are the muscle cells responsible for endurance movements ¹³⁸, ¹³⁹. For example, the story of the tortoise and the hare. Slow-twitch or type 1 muscle fibers are like the tortoise. They don’t produce a lot of power, but they’re also resistant to fatigue and can contract for a long time ¹⁴⁰. Slow-twitch type 1 muscle fibers help with a lot of your daily movements, like walking, cleaning your house, or sitting upright in a chair.

Type 1 muscle fibers get most of their energy (ATP) from aerobic respiration, meaning they need oxygen to function. The oxygen makes the muscle fibers look red, which is why slow-twitch fibers are sometimes called red fibers. Type 1 muscle fibers have a much better blood supply and ability to receive oxygen than type 2 fibers. They also have a high concentration of mitochondria which is the powerhouse of a cell where aerobic respiration takes place.

Because slow-twitch muscle fibers use oxygen to produce energy, they are more resistant to fatigue. Type 1 muscle fibers are responsible for endurance activities such as distance running, swimming, cycling, hiking, low-to-moderate intensity dancing, and walking.

Fast-Twitch muscle fibers

Fast-twitch muscle fibers are the muscle cells responsible for short, powerful movements ¹³⁸, ¹³⁹. Going back to the story between the tortoise and hare, your fast-twitch or type 2 fibers are like the hare. They can produce a lot more force and power for a short time, but they get fatigued fast ¹⁴¹, ¹⁴².

Type 2 muscle fibers are subdivided into type 2X and 2A ¹³⁸.

Type 2X muscle fibers produce force that’s much greater than type 1 muscle fibers ¹³⁸. However, they use anaerobic (without oxygen) metabolic pathways to get their energy (ATP) ¹³⁸. That means they receive less blood flow and oxygen and can only produce force for short periods of time and are highly fatigable ¹⁴³.

Type 2A muscle fibers are like a hybrid of type 1 and type 2X muscle fibers ¹³⁸. Type 2A muscle fibers have elements of both type 1 and type 2X muscle fiber types. For example, type 2A muscle fibers use both aerobic and anaerobic pathways and produce a medium amount of power for a medium amount of time.

Most people have high numbers of type 2A muscle fibers that produce a medium amount of power and have medium fatigue resistance ¹³⁸. Type 2A muscle fibers tend to be influenced more by training because they operate as fast-twitch fibers in untrained people and slow-twitch fibers in endurance-trained people. Rather than specifically trying to target type 2A muscle fibers with training, train for your sport or activity and allow these muscle fibers to adjust automatically ¹³⁹.

When your body moves, it will use slow-twitch type 1 muscle fibers first. Then, if type 1 muscle fibers can’t produce enough force, the body will use fast-twitch type 2X and 2A muscle fibers to get more power.

So, if your fitness goals involve strength and power, you’ll want to focus on training type 2 muscle fibers. Technically, any resistance training will train both type 1and type 2 muscle fibers, but training with heavier loads at least 70% of one-repetition maximum (1RM) or lighter weights with explosive tempos are the best ways to activate and train type 2 fibers. These muscle fibers also tend to achieve muscle growth easily, which can be important for bodybuilders.

Note that 1 repetition maximum (1RM) is the heaviest weight a person can lift once while using proper form and performing a full range of motion. 1RM (1 repetition maximum) is a reliable way to measure your overall muscular strength and is often used by strength and conditioning coaches. 1RM is used to determine the appropriate load and intensity for resistance training. For example, if you want to do 5 back squats, you can calculate the weight to use by taking 85–90% of your 1RM.

Strength- and power-based activities typically use more type 2X and some 2A muscle fibers. These activities require a large amount of force to be produced at once with little need for fatigue resistance. Some activities that use type 2 muscle fibers include ¹³⁸:

• Sprints. A sprint workout is a training routine that involves alternating short, high-intensity bursts of exercise with rest or low-intensity exercise. Sprinting is an anaerobic exercise that involves running at top speed for a short time. Your body can’t bring in enough oxygen quickly enough to provide energy for the movement. This produces lactic acid, which builds up in your blood and limits how long you can sprint. Sprinting helps you run faster and for longer by increasing your lactate threshold. Sprinting also builds muscle in your legs and stimulates growth throughout your body.
• Olympic weightlifting. Olympic weightlifting is an Olympic sport where athletes attempt to lift a barbell loaded with weight plates in a single lift. The two lifts in Olympic weightlifting are the snatch and the clean and jerk
• Powerlifting. Powerlifting focuses on lifting the most weight possible in three lifts: bench press, squat and deadlift.
• Plyometrics. Plyometrics are a type of exercise that uses explosive movements to build muscle power and improve physical performance. Plyometric exercises can include jumping, running, kicking, and throwing. Some examples of plyometric exercises include:
  • Box jumps: Jump up and onto a box while lifting your arms for momentum, then jump back down
  • Squat thrusters: Start in a high plank position, then jump your feet forward into a squat
  • Jumping lunges: Stand with your feet shoulder-width apart, then jump while bringing one leg in front of you and the other behind you
  • Squat jumps: Start standing on your toes, then flex your hips and jump up

To stimulate fast-twitch type 2 muscle fibers, lift higher loads (more than 70% one-repetition maximum [1RM]) at lower repetitions (1 to 12) or use lighter weight with explosive tempos. Some examples of fast-twitch stimulating exercises include ¹³⁸:

• Heavy barbell squats. Heavy barbell squats are a compound exercise that involves holding a weighted barbell and performing a squat. To do a barbell squat stand with your feet shoulder-width apart, unrack the barbell, and hold it on your upper back. Keep your chest up and back straight, then hinge your hips and knees to lower your body into a squat position.
• Heavy barbell bench presses. A heavy barbell bench press is a weight training exercise that involves using a barbell to press a heavy weight upwards while lying on a bench. Remember to always have a spotter to help you lift safely.
• Medicine ball slams. A medicine ball slam is a full-body exercise that involves lifting a weighted ball overhead and slamming it into the ground. To do a medicine ball slam:
  1. Stand with your feet shoulder-width apart.
  2. Hold the ball in both hands at your torso.
  3. Squat down slightly.
  4. Inhale and press through your heels to stand up on the balls of your feet.
  5. Extend your knees and hips as you rise to lift the ball overhead.
  6. Slam the ball down between your feet with as much force as you can.
  7. Catch the ball on the rebound or pick it up for repetition.
• Chest pass. A chest pass is a passing technique in basketball and netball where a player holds the ball at chest level and throws it to another player, usually without the ball touching the floor.
• Box jumps. A box jump is a type of exercise that involves jumping from the ground onto an elevated surface, such as a box. Box jumps are a high-impact exercise that can help improve your lower body strength and speed, as well as your vertical jump range.

Fast-twitch fibers can also recruit slow-twitch fibers: endurance training at high-intensity intervals can be effective in improving aerobic power ¹⁴⁴, ¹⁴⁵.

Tapering during training programs (reducing volume and intensity), can also improve the strength and power of type 2A fibers without decreasing type 1 performance ¹⁴⁶.

One study investigated muscle fiber changes in recreational runners training for a marathon ¹⁴⁶. After 13 weeks of increasing mileage and a three-week tapering cycle, not only did the functions of type 1 and type 2A fibers improve, but type 2A continued to improve significantly during the tapering cycle ¹⁴⁶.

The science behind muscle building

It is hypothesized that there are 3 three main mechanisms involved in the process of inducing muscle hypertrophy to resistance exercise ¹⁴⁷, ¹⁴⁸, ¹⁴⁹, ¹⁵⁰. These are:

1. Muscular Damage
2. Metabolic Stress
3. Muscular tension.

Muscular Damage

Exercise training can result in localized damage to muscle tissue, which under certain conditions is theorized to generate a hypertrophic response ¹⁴⁷, ¹⁵¹. When you perform an activity that is harder in some way than your current ability, that activity produces stress within one or more body systems that consequently requires these systems to adapt. It does this in many ways, from chemical to structural alterations, but the underlying principle remains the same ¹⁵², ¹⁵³, ¹⁵⁴, ¹⁵², ¹⁵¹, ¹⁵⁵.

Stress causes an adaptation within a particular body system, which the body then responds to by reorganising and repairing itself to be better prepared for next time ¹⁵⁶. In order to drive further adaptation, higher stress must be applied to signal to the system that an adaptation is required. The adaptation of the body system is specific to the stress applied, in other words, you adapt in a way that is directly related to the stress experienced ¹⁵⁶. For example, calluses form on your hands as an adaptation to picking things up. They develop on your hands and not on your face because that is the area where the stress was applied. Gradual and planned increases in this cycle of stress, recovery and adaptation are what scientists refer to as progressive overload and it forms the basic principle of almost all human performance-based training around the world ¹⁵⁶. The goal of building muscle is no different.

When you stress muscle tissue appropriately, either through the application of load, volume and time under tension, this creates a certain level of structural and systemic damage within the muscular tissue itself. As a result of that damage, the muscular system reorganises and repairs that tissue to a level above what previously existed. Muscular damage, often as a side effect, creates soreness and inflammation within the tissue and for years it was assumed that more soreness equated to more growth. Thankfully, scientists now understand that not to be the case, despite this misconception still being repeated in many places. That being said, while the level of soreness does not directly correlate to more muscular growth, the basic concept of stress, recovery and adaptation of the muscle tissue is still a factor that must be considered in the process. For years, muscular damage was the be-all and end-all of training, but we now understand several other important factors that contribute to the process of inducing muscle hypertrophy – metabolic stress and muscle tension.

Metabolic Stress

Metabolic stress is the concept of eliciting an influx of metabolic products into the muscle through manipulating reps, sets and rest time in an exercise. More commonly referred to as the “burn” or “pump”, this concept has existed for many decades in bodybuilding styles of training but has only more recently been researched and understood on a scientific level. The hypothesis that currently exists reports that increased metabolic activity in the muscle tissue (specifically metabolite accumulation) improves motor unit recruitment and drives the release of anabolic hormones accelerating muscle hypertrophy ¹⁵⁷, ¹⁵⁴, ¹⁵⁸, ¹⁵⁹, ¹⁶⁰, ¹⁶¹, ¹⁶².

This concept was established through numerous studies where various set and rep range protocols were manipulated at the results closely studied. It was established that the primary driver of metabolic stress is:

• Higher volume exercises of between 10 to 12 repetitions.
• Performed at 70-80% 1RM (1 repetition maximum) for multiple sets. 1 repetition maximum (1RM) is the heaviest weight a person can lift once while using proper form and performing a full range of motion. 1RM (1 repetition maximum) is a reliable way to measure your overall muscular strength and is often used by strength and conditioning coaches. 1RM is used to determine the appropriate load and intensity for resistance training. For example, if you want to do 5 back squats, you can calculate the weight to use by taking 85–90% of your 1RM.
• With only 30 seconds to 1 minute of rest between each set.

While this might seem simple on the surface, how can this be applied on a practical level to your training? The fundamental problem with the metabolic stress model (apart from turning each workout into a hellish nightmare) is that it is very difficult to practically apply during large compound lifts, which should always form the foundation of any good program. You simply cannot perform 6-8 sets of 12 reps with only 1 minute of rest with any meaningful amount of weight (certainly not a true 80% of a 1RM which is advocated in several studies), at the very least not without compromising the form and safety of the trainee. This means that this type of training typically limits itself to isolation-based exercises that neither utilize as much muscle mass nor provide the systemic stress that compound lifts do. This reduces their overall ability to make any substantial change to muscle mass. The danger with this is when programs are designed based purely on this principle and forget to factor in the other primary factors of muscle hypertrophy, you are leaving a huge amount of untapped potential in your training, especially for beginners as well as leaving yourself open to possible injury, overtraining and chronic soreness ¹⁵⁶.

Muscle Tension

The previously mentioned mechanisms of muscle hypertrophy cannot happen without the third being present. Increases in muscular tension are the only reliable and constant factor across all demographics that must be in place for hypertrophy to occur. Mechanically induced tension produced both by force generation and stretch is considered essential to muscle growth, and the combination of these stimuli appears to have a pronounced additive effect ¹⁶³, ¹⁶⁴, ¹⁵⁰. More specifically, muscular tension is the contraction of the sarcomeres within the muscle tissue to produce force. Yet it should be noted that hypertrophy from muscular tension can be produced in the absence of both significant metabolic stress and muscular damage. How much muscular tension and under what conditions are where the debate lies ¹⁵⁶.

Theoretically, muscular tension is produced whenever a muscle is under contraction, but in the gym, you typically obtain muscle tension under two conditions.

1. When heavy weight is lifted for lower repetitions, or
2. When lighter weights are lifted for higher repetitions but taken very close to failure.

These two events are similar in a sense that the repetitions involuntarily slow down the further through the set you move and both events can, and will, create fatigue forcing you to exert more force and effort into finishing the set ¹⁵⁶. However, there are some less obvious differences between the two in terms of their performance.

A heavy set of say 5 at 90% 1RM (1 repetition maximum), requires more motor unit recruitment from the start of the set, due to the outright force production necessary to lift the weight in the first place. The more force you must produce, the more motor units must be recruited (particularly the larger type 2 fibres). In a lighter, but still taxing 12RM set (a repetition maximum of 12, which is the most weight you can lift and perform 12 repetitions of an exercise with proper form), the first 6 reps are submaximal, meaning that they do not require close to the maximal effort to move. However, as the set continues, you must then call into recruitment of more motor units (type 2) to complete the set. A moderate repetition scheme, like 8 to 12 repetitions per set with 60% to 80% of 1RM, is best for optimizing hypertrophic gains ¹⁶⁵. Some research suggests that alternating between blocks of 10-12 reps at 70% and blocks of higher intensity, like 3-5 reps with 90% 1RM, can achieve similar muscular gains.

The question is then placed as to what method do you choose? Both can have significant results in the production of muscle hypertrophy and can generally be safely used by the most individuals. There are several things such as time, specific goals, and access to equipment, that all play into this. You want to choose the method that give you the most bang for your buck in the most efficient way possible.

Firstly, heavy sets feel heavy because they ARE heavy. They also give the added benefit of calling into contraction a higher number of motor units in order to move the weight. Secondly, you know that hypertrophy occurs as a result of more motor units being used, but also the ability to produce maximal force increases in those muscle fibers when they are called into contraction. In other words, the adaptation occurs in both the size of the muscle but also in its ability to produce force.

In contrast, lighter weights taken close to failure may feel difficult, and in some cases, will produce a good hypertrophic response. However, this method pales in comparison to the increase in overall force production of heavier weights completed for lower reps. The problem here is that due to the limited amount of adaptation towards more force production, the weight quickly becomes the bottleneck to continued progress. If you are getting bigger, but are not able to go up in weight, how do you continue to drive progress without now changing the rep ranges away from those best suited to continue to build muscle?

The point being made here is that a lot of time beginners looking to gain muscle will jump immediately into a highly complicated multi-factor program that is backed by “science” only to spend the next year on a hamster wheel making little to no progress. Getting the foundations right in any training regime is fundamental before you start debating the ins and outs or finer details, and anyone who has been training for any amount of time generally arrives at the same conclusion eventually.

The reality is that all you need at the beginning is a simple program that focuses on large compound lifts which utilize and progressively overload as much muscle mass as possible over the full range of motion.

Many people have wasted years in the gym only to find out that the answer was simple, not complexity. As your training progresses and goals become more clearly defined, then complexity can be added, but don’t waste precious time by trying to get complicated before you have to.

What builds muscle the most?

The best way to build muscle is to lift heavy weights and have proper nutrition. Weight training is the best way to keep the muscle mass you have and even increase your muscle mass. You’ll also need to consume more protein than your body removes to build muscle. Getting enough sleep is also important for muscle growth because your muscles recover and grow while you’re asleep. Try to get 8 to 10 hours of sleep per night. The National Sleep Foundation, an organization of doctors and researchers who specialize in sleep, recommends that adults (between the ages of 18 and 64) achieve between 7 to 9 hours of sleep per night ¹⁶⁶. If you’re older than 65, you may need a little less: seven to eight hours is recommended.

For both men and women, sleeping less than 6 hours per night could result in higher belly fat levels. A lack of sleep can elevate the sympathetic nervous system (SNS), responsible for stimulating the metabolism to produce the energy for physical activity. Insufficient sleep could boost the hormones cortisol and epinephrine (adrenaline), which help release free fatty acids that you use for energy. When there is low physical activity, the free fatty acids can deposit in the adipose (fat) tissue of your abdominal region resulting in additional belly fat ¹⁶⁷.

Another way that insufficient sleep could lead to weight gain is through the production of specific hormones. Grehlin is a hormone responsible for stimulating hunger. Leptin performs the opposite function and tells the body when it has had enough food intake. Poor sleep is associated with leptin levels decrease and ghrelin rises, potentially resulting in an increase in appetite and over-eating ¹⁶⁸. In addition, staying awake late into the evening allows you more opportunities for mindless snacking on calorically-dense food. Furthermore, the added fatigue from lack of sleep may also lead you to skipping out on exercising, another setback for reaching your weight loss goals.

Insufficient sleep could also impair your body’s ability to properly recover from a challenging strength training workout designed to promote muscle growth. Growth hormone (GH), an anabolic hormone responsible for repairing muscle tissue damaged during exercise, is produced during stage 3 of Non-Rapid Eye Movement (NREM) sleep; achieving optimal sleep could be helping muscles grow ¹⁶⁹.

While sleeping, your body will experience multiple cycles of sleep, each of which can last between 70 to 120 minutes; there are three stages of Non-Rapid Eye Movement (NREM) sleep and a fourth stage of Rapid Eye Movement (REM) sleep and over the course of one night, your body goes through the sleep stages every 90 minutes or so ¹⁷⁰.

The Sleep Stages ¹⁷¹:

• Stage 1. Stage 1 of the sleep cycle is the lightest phase of sleep and generally lasts about seven minutes. The sleeper is somewhat alert and can be woken up easily. During this stage, your heartbeat and breathing slow down while your muscles begin to relax. Your brain produces alpha and theta waves.
• Stage 2. In Stage 2, your brain creates brief bursts of electrical activity known as “sleep spindles” that create a distinct sawtooth pattern on recordings of brain activity. Eventually, the waves continue to slow down. Stage 2 is still considered a light phase of sleep, but the sleeper is less likely to be awakened. Heart rate and breathing slow down even more, and the body temperature drops. Stage 2 lasts around 25 minutes.
• Stage 3. Stage 3 represents your body falling into a deep sleep, where slow wave sleep occurs. Your brain produces slower delta waves, and there’s no eye movement or muscle activity. As your brain produces even more delta waves, you enter an important restorative sleep stage from which it’s difficult to be awakened. This phase of deep sleep is what helps you feel refreshed in the morning. It’s also the phase in which your body repairs muscle and tissue, encourages growth and development, and improves immune function.
• Rapid Eye Movement (REM) Sleep. About 90 minutes after falling asleep, your body enters REM (Rapid Eye Movement) sleep and is named so for the way your eyes quickly move back and forth behind your eyelids. REM sleep is thought to play a role in central nervous system (brain and spinal cord) development in infants, which might explain why infants need more REM sleep than adults. REM sleep pattern is characterized by dreaming, since your brain is very active during this stage. Physically, your body experiences faster and irregular breathing, increased heart rate, and increased blood pressure; however, your arm and leg muscles become temporarily paralyzed, stopping you from acting out your dreams. REM sleep increases with each new sleep cycle, starting at about ten minutes during the first cycle and lasting up to an hour in the final cycle. Stage 4 is the last stage before the cycle repeats. This sleep stage is critical for learning, memory, daytime concentration, and your mood.

While all sleep stages are important, Stage 3 and REM sleep have unique benefits. One to two hours of Stage 3 deep sleep per night will keep the average adult feeling restored and healthy ¹⁷¹. If you’re regularly waking up tired, it could be that you’re not spending enough time in that deep sleep phase. Meanwhile, REM sleep helps your brain consolidate new information and maintain your mood – both critical for daily life ¹⁷¹. Talk to your doctor if you feel you are not getting the restful sleep that you need.

How to build muscles faster?

Muscle building also called muscle hypertrophy is defined as an increase in skeletal muscle size is the process of increasing muscle size, density, and shape, typically through weightlifting and resistance training ¹⁷², ¹⁷³, ¹⁷⁴, ¹⁷⁵, ¹⁷⁶, ¹⁷⁷, ¹⁷⁸. Research has shown that in order to increase muscle mass, stress must be put on the body, leading to increased hormone release, and increased flow of nutrients into the muscle, and with rest, muscles will grow ¹⁷⁹, ¹⁸⁰, ¹⁸¹, ¹⁸², ⁴⁰, ¹⁸³, ¹⁸⁴, ¹⁸⁵.

To get a bigger muscle, you can:

• Use a reps-and-rest cycle. Aim for 6–12 reps per set, with 60–90 seconds of rest between sets.
• Lift heavy weight. Lifting too light a weight won’t lead to the same definition gains.
• Vary your exercises. This will help you work different muscle fibers.
• Progressively increase the resistance over time.
• Muscle growth is typically experienced after 6 to 7 weeks of resistance training ¹⁸⁶. Muscle growth is more common in fast-twitch than in slow-twitch muscles. Type 2A fibers exhibit the greatest growth, more so than type 2B and type 1 fibers.
• Eat a healthy diet rich in macronutrients, especially protein ⁴⁸, ⁴⁹.

However, gaining lean body weight is a slow process that takes months and years rather than days and weeks. Most muscle tissue is made up of different kinds of proteins. When you lift heavy loads, your muscles tear and your body experiences metabolic stress ¹⁸⁷. In response to this, your body tells the proteins to increase, and the muscles slowly grow ¹⁸⁷. Then, to keep growing your muscles, you have to keep increasing weightlifting volumes over time ¹⁸⁷. A beginner new to weightlifting who uses full body workouts three times a week can expect to build 1/2 to 1 pound per week or 6 to 12 pounds of muscle in 3 months. An experienced lifter can build 1/4 to 1/2 pound per week or 3 to 6 pounds of muscle in 3 months.

There are several ways you can train to make your muscles bigger. Most hypertrophy training plans focus on lifting heavier loads for a smaller number of reps and sets. However, different bodies might respond differently to the same programs, so there is usually some trial and error when finding your optimal training plan.

According to the National Academy of Sports Medicine (NASM), muscle building training can sometimes result in overuse injuries like tendonitis or tendinosis or low-grade muscle tears, especially when you don’t properly rest and recover ¹⁸⁷. Lifters who try to lift too much or have poor form can get more serious acute injuries like ruptured discs, ligament tears, fractures, or high-grade muscle tears ¹⁸⁷.

Most of these risks can be avoided if you follow a structured program from a qualified trainer who knows your capabilities ¹⁸⁷. In fact, muscle building is a more advanced form of strength training. According to the Optimum Performance Training Model (OPT Model), a 5-phased fitness training system developed by Dr. Mike Clark to guide National Academy of Sports Medicine (NASM) personal trainers to help their clients improve their performance, training, and recovery ¹⁸⁸. The Optimum Performance Training Model (OPT Model) is based on human movement science principles, including biomechanics, kinesiology, and exercise physiology. It combines a variety of exercises, including:

• Flexibility training
• Cardiorespiratory training
• Core training
• Balance training
• Plyometric training
• Speed, agility, and quickness training
• Resistance training
• Stabilization endurance training

The Optimum Performance Training Model (OPT Model) progresses people through 5 phases ¹⁸⁸:

1. Phase 1 Stabilization and Endurance. Stabilization and Endurance is the foundation of the entire OPT Model. Before you start building training, you should have good stability, muscle endurance, and optimal movement patterns to prevent injury. During this first phase, you will perform 12 to 20 repetitions per set, your movement speed will slow down, and the intensity/weight used for exercises reduced to promote muscular endurance and ensure correct form and technique. Phase 1 is a great starting point for those who are new to training and is an opportune time to do questionnaires and fitness assessments to determine goals, establish baselines for training, and identify any movement compensations, respectively. And, for more experienced clients, Stabilization and Endurance phase is a great to include in their program to add different stresses and challenges to their body and will also become a critical phase to cycle back through between training periods in the other phases. Reinforcing correct movements in this phase can lead to strength gains — even with lighter weights — because of enhanced joint and postural control, and coordination. When progressing in this phase, a primary focus is on increasing proprioceptive demand (controlled instability) of the exercises, rather than just increasing the amount of weight you use.
2. Phase 2 Strength Endurance. The Strength Endurance Phase gives you the chance to acclimate to heavier weights and higher training intensities. Workouts in the Strength Endurance Phase use superset techniques in which you will follow a more traditional strength exercise such as a bench press with an exercise that has similar biomechanical motions but requires more stabilization to perform (like a stability ball push-up). The Strength Endurance Phase is the logical next step from Phase 1 for increasing the intensity of your workouts. Sets increase to 2 to 4, repetitions will stay high (8-12 per exercise / 16-24 per superset). The supersets combined with decreased rest periods will elevate the challenge considerably leading not only to noticeable improvements in your strength and endurance but more significant your calorie expenditure too.
3. Phase 3 Muscular Development/Hypertrophy. Phase 3 of the OPT Model is all about building strength and developing muscle. Muscular Development/Hypertrophy training is ideal for the adaptation of maximal muscle growth, by focusing on higher volumes of work at moderate-to-high intensity levels and with minimal rest periods between exercise sets. These training variables contribute to cellular changes that result in an overall increase in muscle size. If caloric intake is appropriate, the increased intensities and training volumes, and decreased rest periods experienced in this phase also make it great for those who aspire to change their body composition through fat/weight loss. Typically, workouts in this phase involve performing 3 to 6 sets of 6 to 12 reps per resistance exercise at intensities ranging from 75 to 85% of your one-rep max (the heaviest weight you can lift for just one go or for a single lift) or 1RM. You’ll typically be lifting at 85 to 100% of your one-rep max (1RM), so knowing your limits ensures your workouts remain challenging yet safe. And, don’t make the mistake of thinking your max on one lift applies to another – your bench press one-rep max (1RM) might be worlds apart from your back squat. Go here for a free online One Rep Max (1RM) calculator (https://www.nasm.org/resources/one-rep-max-calculator). You can also use the Standard One-Rep Max (1RM) table below. The “standard” one-rep max (1RM) values can differ based on age, gender, weight, training history, and other factors. Below is a generalized range for an average adult male, assuming he’s in decent shape but not necessarily an elite athlete.
4. Phase 4 Maximal Strength. Phase 4 is geared towards enhancing your ability to produce maximal muscular force. Accomplishing this requires maximal efforts and lifting near-max/maximal loads during resistance training—ranging anywhere from 85 to 100% of your one-rep max for 1 to 5 repetitions. While similar to Muscular Development training in scope, developing maximal strength largely depends on neuromuscular adaptations resulting from consistently and progressively overloading muscles with higher intensities (loads). Because you will be lifting very heavy weights (near-max/maximal loads) in this phase, longer rest periods between exercise sets and higher volumes of training are usually required to optimize strength gains.
5. Phase 5 Power. The 5th phase of the OPT Model focuses on using high force and high velocity exercises to increase power. One method to improve power is to perform supersets with contrasting loads. Like the supersets outlined and used in Phase 2 of the OPT Model, supersets in 5th phase will consist of two biomechanically similar exercises performed back-to-back. The first exercise should challenge near-max/maximal strength for 1 to 5 reps, and the second exercise should involve and challenge moving relatively low loads as fast and explosively as possible for 8 to 10 reps. The rationale for this sequence is to activate and tap into as many muscle fibers as possible with the maximal lift, while utilizing explosive exercises directly after to improve how quickly and efficiently those muscle fibers contract. Keeping with the upper body exercise theme used previously, an example Phase 5 superset is performing a bench press followed by a medicine ball chest pass.

Table 5. Standard One-Rep Maximum (1RM)

Experience Level	Deadlift (kg)	Bench press kg)	Squat
Beginner	60-100	40-70	50-85
Intermediate	100-140	70-100	85-125
Advanced	140-180	100-130>	125-170
Elite	180	130	170

Footnote: Always consult with a fitness professional to set realistic and safe goals.

[Source ¹⁸⁹ ]

The Optimum Performance Training Model (OPT Model) should be thought of as a staircase, guiding you through different physical adaptation levels. This journey will involve going up and down the stairs, stopping at different steps, and moving to various heights, depending on your goals, needs, and abilities.

Table 6. Optimum Performance Training Model (OPT Model)

Summary of the Optimum Performance Training Model (OPT Model)
Level	Phase	Primary Adaptations	Primary Methods of Progression
Stabilization	1. Stabilization Endurance Training	Mobility and flexibility Core and joint stabilization Postural alignment and control Muscular and aerobic endurance	Progress exercises proprioceptively (controlled, yet unstable) Increase the complexity of exercises once basic movement patterns have been established.
Strength	2. Strength Endurance Training	Core strength and joint stabilization Muscular endurance and prime mover strength	Decrease rest periods. Increase the volume of exercises (reps + sets). Increase the load (weight) of resistance training exercises. Increase the complexity of resistance training exercises.
	3. Hypertrophy Training (Muscular Development Training)	Core strength Muscular strength and hypertrophy	Increase the volume of exercises. Increase the load of resistance training exercises. Increase the complexity of resistance training exercises.
	4. Maximal Strength training	Core strength Maximal muscular strength	Increase the load of resistance training exercises. Increase the sets of resistance training exercises.
Power	5. Power Training	Core strength Maximal muscular strength Rate of force production	Increase the load of resistance training exercises. Increase the speed (repetition tempo) of exercises. Increase the sets of exercises.

[Source ¹⁸⁸ ]

To build muscle, you can:

• Train consistently: Train 2 or 3 times per week to give your muscles time to recover. Commit to a regular training routine and don’t take weeks off.
  Make your workouts short and intense rather than long and leisurely.
• Eat a protein-rich diet: Eat lean protein sources like chicken, fish, lean meat, and plant-based protein powder. The recommended protein intake is 0.8 to 1 gram per kilogram of body weight per day ¹⁸. For strength training athletes adequate protein intake should range between 1.2 and 1.7 grams of protein per kilogram of body weight per day or 0.5 to 0.8 grams per pound of body weight ¹⁹, ²⁰, ²¹, ²². Try to eat protein within 30 minutes of a workout.
• Get enough rest: Your body releases growth hormones during sleep and rest, which helps muscles grow and repair.
• Do resistance training: Use weights, resistance bands, or your own body weight to build muscle. You can try:
  • Compound exercises that work multiple muscle groups, like squats and bench presses
  • Body weight exercises like pushups, pullups, lunges, and planks
• Progress your strength training: Increase the amount of weight you lift.
• Find a qualified training partner: A gym instructor or personal trainer can help you do exercises correctly and reduce your risk of injury.
• Mix in cardio: Short, sharp cardio can help burn fat.

You can expect to see noticeable muscle growth after 8 to 12 weeks, but it depends on many factors, including: nutrition, intensity, frequency, age, genetics, and sex.

What is the best protein powder supplement?

Creatine (N-[aminoiminomethyl]-N-methyl glycine) is a non-essential amino acid–like compound that is produced in your liver, kidney, pancreas, and possibly your brain from the biosynthesis of the essential amino acids methionine, glycine, and arginine (with folate and vitamin B 12 as catalysts), or obtained from dietary sources ¹⁹⁰. The primary dietary sources of creatine are high-protein foods including red meats, fish, and poultry. Once synthesized or ingested, creatine is transferred from the plasma through the intestinal wall into other tissues by specific creatine transporters located in skeletal muscles, the kidney, heart, liver, and brain. An average 150lb male has a creatine pool of approximately 120-140gms. Typically, humans manufacture about 1 gram/day of creatine, obtains 1 gram from food (muscle meats contain ~300-500 mg per 100gm serving), and loses about 2 grams per day. Therefore, under normal circumstances, creatine levels are fairly constant.

Creatine is mainly stored in your muscles with a small amount stored in your brain as well. It’s naturally found in foods such as red meats, fish, and poultry. In a normal diet that contains about 1-2 grams of creatine per day, muscle stores are only about 60-80% saturated. Vegans/vegetarians will likely have lower stores since natural sources mainly exist in animal meats.

The phosphorylated form creatine, creatine phosphate, provides an immediate energy source for your brain and muscles, and therefore, the primary reasons for supplementation are to increase, rapidly replete, and prolong this energy source to increase the metabolic capacity of these target tissues, such as the capability of a muscle to contract more powerfully longer and heal faster.

Creatine is one of the most widely studied supplements namely for its ability to increase muscle mass! Research has shown that increases in muscle mass can occur in as little as 4 weeks by supplementing with creatine in the diet.

Creatine as a dietary supplement is a tasteless, crystalline powder that readily dissolves in liquids and is marketed as creatine monohydrate or as a combination with phosphorous (creatine phosphate) ¹⁹¹. The majority of creatine (95%) is stored in skeletal muscle (fast twitch, type 2): two-thirds in a phosphorylated form and one-third as free creatine ¹⁹². Creatine serves as an energy substrate for the contraction of skeletal muscle. The intention of creatine supplementation is to increase resting phosphocreatine levels in your muscles, as well as free creatine, with the goal of postponing fatigue, even briefly, for sports-enhancing results ¹⁹³. The goal of creatine monohydrate supplementation is to increase your muscle levels of creatine and speed the regeneration of creatine phosphate beyond what can practically be accomplished by diet alone. Creatine monohydrate supplementation has been shown to increase skeletal muscle total creatine content >15% and up to 24%, and >9% in the brain.

Creatine monohydrate is currently the most effective performance enhancement supplement for people seeking to improve their high-intensity exercise capacity (i.e., acute performance enhancement including the quality of each training session and production on game/competition day), and/or increase exercise-induced lean body mass. Creatine monohydrate is generally safe and can help you build more muscle mass ¹⁹³, ¹⁹⁴, ¹⁹⁵, ¹⁹⁶, ¹⁹⁷, ¹⁹⁸. However, always check with your doctor before starting any supplement.

Creatine is one of the most widely used dietary supplements. Athletes, body builders, and military personnel use creatine to enhance muscle mass and increase strength. Creatine is also used as an ergogenic aid to improve performance of high-intensity exercise of short duration ¹⁹⁹, ²⁰⁰, ²⁰¹. Creatine’s popularity as a dietary supplement was further increased by a 2006 study demonstrating its positive effect on cognitive and psychomotor performance ²⁰².

Experiments among athletes and military personnel indicate that creatine taken at levels commonly available in supplements produces minimal, if any, side effects ²⁰¹, ²⁰³. Using evidence from well-designed, randomized controlled human clinical trials of creatine, Shao and Hathcock ²⁰³ concluded that chronic intake of 5 g/ day of creatine was safe and posed no significant health risks.

Muscle creatine concentrations are increased by 20% with creatine monohydrate supplementation ¹⁹². Creatine monohydrate supplements increase lean body mass, as well as strength, power and effectiveness in short-duration, high-intensity exercises ²⁰⁴. The increase in body mass may be a result of the increase in intracellular water related to the osmotic properties of creatine ²⁰⁵. Studies on creatine monohydrate supplementation have shown short-duration improvements in sports performance and strength: specifically, in maximum-intensity exercises, muscle power, number of repetitions, muscle endurance, speed and total strength ²⁰⁶.

The use of creatine monohydrate can yield increases in power during short sprints of maximum intensity, which can be even more evident when repeated sprints are accompanied by short recovery periods ¹⁹⁸. Furthermore, with creatine monohydrate supplementation, effects are also observed in muscle glycogen stores ²⁰⁵. This is important because the availability of muscle glycogen is the main determinant of sports performance in resistance exercises, and its depletion can lead to muscle fatigue ²⁰⁷. In addition, creatine monohydrate is one of the few sports foods supplements or ergogenic aids (substance used for the purpose of enhancing performance) with health claims authorised by the EFSA and the European Commission (EC), due to its evident effects on the health and sports performance of athletes ²⁰⁸, ²⁰⁹.

The approved health claims are ‘Creatine increases physical performance in repeated bursts of high-intensity exercise in the short term’ and ‘Daily creatine consumption can enhance the effect of resistance training on muscle strength in adults over the age of 55’. These health claims refer to the 3-g dose of creatine monohydrate ²⁰⁹. Resistance training should be performed at least three times per week for several weeks, at an intensity of at least 65–75% of one repetition maximum (1RM). The target population is adults over the age of 55, who are engaged in regular resistance training ²⁰⁹. Creatine in combination with resistance training and improvement in muscle strength ²⁰⁹.

The goal of creatine monohydrate supplementation is to deliver a greater and prolonged accrual of gains, as opposed to a non-supplemented state, that can translate to the “field of play” (specific sport activities) because continuous better workouts allow greater and continuous improved muscular adaptations. To see the fastest results, a loading protocol for creatine is often recommended. For most individuals, supplementing 5 grams of creatine per day (or about 0.3g/kg) four times daily for 5-7 days can fully saturate stores. After a loading protocol, stores can be maintained by ingesting about 5 grams per day (for larger individuals, doses of 10g per day may be needed).

In regard to timing, creatine offers the most benefit when consumed after exercise since it can help facilitate water and carbohydrates back into the muscles more quickly (faster recovery).

How does creatine monohydrate supplement improve performance and muscle growth?

Creatine monohydrate supplementation works by enhancing your body’s natural ability to create adenosine-triphosphate (ATP) is the energy molecule produced in your body that allows you to perform work.

Adenosine-triphosphate (ATP) is often called the “energy currency” of the cell because it provides energy for many processes, including:

• Muscle contraction
• Nerve impulse transmission
• Protein synthesis
• Biosynthesis
• Motility
• Maintenance functions

The human body can store ~100 grams of creatine at a given time, which is a relatively small amount considering how important it is to generating ATP (adenosine-triphosphate). Supplementing with creatine can increase your body’s creatine stores by ~30%, which increases the overall capacity of your phosphocreatine pathway (ATP production pathway). Creatine monohydrate supplement helps you produce more energy for better workouts and recover faster/better.

During all-out high-intensity activities lasting 4 to 15 seconds (e.g., jumping, sprinting, weightlifting, etc.) ATP is rapidly depleted but declines very little until stores of creatine phosphates are used. Therefore, creatine phosphates, with its high-energy phosphoryl transfer potential, serves to maintain intracellular adenosine triphosphate (ATP) levels. Creatine monohydrate supplementation significantly increases anaerobic capacity by raising the natural levels of creatine phosphates allowing intracellular concentrations of ATP to be maintained at higher levels for longer periods, permitting athletes to maintain greater training intensity and quality/quantity of each workout. Maintaining higher quality workouts throughout an entire training period leads to greater overall performance gains immediately that also compound over time, including skeletal muscle growth based on training protocols.

Creatine monohydrate supplementation also delays fatigue by reducing exercise-induced decreases in muscle pH, thereby buffering lactate and/or allowing less reliance on glycolysis.

Creatine monohydrate supplementation has been shown to:

1. Improve body composition among resistance training athletes
2. Improve performance over high intensity repeated bouts of exercise
3. Increase strength in short-time domain exercises

The best way for athletes to take creatine is to take between 3 to 7 grams per day, with ~5 grams per day being the appropriate average dose for most people. Individuals who are smaller can consume closer to 3 grams per day, while individuals who are larger can consume closer to 7 grams per day. Typical creatine monohydrate supplementation using standard dosing protocol (.045 g/pound body weight per day) in exercisers for 10 weeks: improved strength, body composition (lean body mass) and muscle size versus no supplementation.

Creatine monohydrate supplementat may also work through other unique muscle building mechanisms related to recovery, development and muscular adaptations during the supplementing phase. These related mechanisms of creatine monohydrate supplementat may include changes in gene expression, satellite cell proliferation, insulin-like growth factor signaling, increase in growth hormone, alterations in myogenic transcription factors leading to a reduction in serum myostatin (muscle growth inhibitor), improved neuromuscular function (facilitating the reuptake of calcium ion into sarcoplasmic reticulum), and as mentioned above, reduced exercise induced blood lactate.

Finally, creatine monohydrate supplementation may also participate in reducing certain types of muscle damage (not all) from high intensity resistance training and endurance exercise allowing more complete recovery before subsequent exercise bouts.

Creatine monohydrate supplementation increases the metabolic capacity of the target tissues, such as the capability of a muscle to contract more powerfully longer and also helps with faster complete recovery.

Can creatine monohydrate supplement improve aerobic performance?

Possibly through energy partitioning (where energy is drawn from), heat regulation and recovery. Relatively little has been studied or benefits quantified using creatine monohydrate supplementation in aerobic activities due to creatine monohydrate supplementation targeting the ATP-phosphocreatine energy system. If there is a benefit, it is probably related to a change in energy substrate utilization (when creatine phosphates levels are increased by creatine monohydrate supplementation), at least during the early phase of aerobic activity that might help decrease time to exhaustion.

In aerobic/endurance activities, creatine monohydrate supplementation may improve energy usage, thermoregulation and overall recovery including glycogen restoration. Roberts et al. ²¹⁰ found creatine monohydrate supplementation to augment muscle glycogen stores post exercise to potentially enhance the next bout of endurance activities. And finally, another mechanism in which creatine monohydrate supplementation may indirectly benefit aerobic activities is the ability of creatine to attenuate cardiovascular and thermoregulatory responses during prolonged exercise in the heat.

How do I use creatine monohydrate supplement to get maximum results?

• Effective Creatine dosing: Load 5g four times per day for first 5 to 7 days; then 3 to 10g per day maintenance till end of training phase cycle.
• Creatine Loading phase: The most common and successful creatine monohydrate supplementation protocol starts with a loading phase of 20g of creatine monohydrate per day or 0.14 g of creatine monohydrate per pound of body weight per day split into four daily doses of 5g each for 5 to 7 days ingesting each dose with meal/shakes to improve creatine skeletal retention. Following the loading period, continue with the maintenance phase of 3 to 5g per day or for larger athletes 5-10 g per day (or 0.04 g of creatine monohydrate per pound of body weight per day), for the duration of the supplementation period. The length of the supplementation period would be based on the goal, but generally last 12 to 16 weeks and cycled throughout the year in combination with intense training for competitive athletes.
• Each creatine monohydrate supplementation dose should be accompanied with some form of carbohydrate or protein to maximize skeletal muscle uptake/retention.

On training days, use one dose before workout and one after with meals/drinks. May mix with your pre/post training formula. On non-training days, take one dose with a morning meal and one dose with an evening meal if using 2 doses for maintenance, otherwise one dose with any meal. To maximize uptake and using multiple doses, creatine monohydrate supplementation intake should be spread as evenly as possible throughout the day with carbohydrate and/or protein containing meals or shakes.

The safety of short and long-term creatine monohydrate supplementation use is well established in healthy users using correct dosing. In 25 years with over 1000 clinical trials, creatine monohydrate supplementation has been shown to be safe and effective when taken as directed in all healthy adult populations.

What are high protein foods?

In general, animal-based protein foods such as eggs, dairy, meat, and seafood provide all nine essential amino acids in adequate amounts ¹. Soy-based foods are unique because they are tasteless and provide all 9 essential amino in sufficient quantities ¹. Most other plant foods, including whole grains, nuts, legumes, and seeds, possess high levels of some amino acids and low amounts of others ¹. However, it would be wrong to assume that animal-based foods provide more protein than plant-based ones. A cup of tofu contains the same number of grams of protein as 3 ounces of steak, chicken, or fish ¹. A half-cup of lentils has more grams of protein than an egg.

Not all plant foods are low in the same amino acids, so eating various plant-based foods can provide all 9 essential amino acids ¹. For example, pairing protein sources like rice and beans, hummus, pita bread, or oatmeal topped with almond butter. However, regarding volume, it may be necessary to eat more plant-based foods to get a similar amount of protein and amino acid profile provided by animal-based proteins ⁸.

Foods that have protein

Protein foods include ¹⁰, ¹¹, ¹², ¹³:

• Animal-based protein foods: Red and white meat (pork, beef, chicken, turkey, duck), seafood (fish, shrimp, oysters, clams, and scallops), eggs, milk, yogurt, and cheese. Animal-based protein sources, such as meat and dairy products, contribute zinc, vitamin B12, vitamin D, calcium, phosphorus, and iron. Meat and poultry foods should be lean or low-fat, like 93% lean ground beef, pork loin, and skinless chicken breasts. Fish is nutritious, providing energy (calories), protein, selenium, zinc, iodine and vitamins A and D (some species only). Fish is also an excellent source of omega-3 fatty acids (good fats), which are well known for their health benefits and are essential for life. Eating fish regularly can reduce the risk of a range of diseases from childhood asthma to heart disease, cardiovascular diseases and prostate cancer. Choose seafood options that are higher in healthy fatty acids called omega-3s fatty acid and lower in methylmercury, such as salmon, anchovies, and trout. And stay away from processed meats or artificial (fake) meat.
• Plant-based protein foods: Nuts and nut spreads such as almond butter, peanut butter, soy nut butter, seeds (sunflower seeds), beans, peas, legumes, lentils, soy products, soy milk, and tofu. Plant protein foods, such as legumes (including soybeans and pulses), nuts, seeds, and cereal grains contribute to dietary fiber, potassium, folate, vitamin E, and magnesium. Peanuts and peanut butter are high in protein, folate, magnesium, and vitamin E. Legumes can also contribute significant non-heme iron to diets ¹⁰.

The Dietary Guidelines for Americans recommend a variety of protein foods from both animal and plant sources in healthy dietary patterns ⁹. The Dietary Guidelines for Americans also recommend a variety of nutrient-dense protein foods from both plant (beans, peas, lentils, and cereal grains) and animal sources (lean meat, poultry, fish, eggs, as well as low-fat dairy products) to ensure adequate nutrient intake ⁹. You should try to include at least one protein-rich food with every meal. Eating foods high in protein can help you build strength and recover more quickly if you’ve been sick.

Here are some examples of protein-rich foods:

• Chicken breast: A 3-ounce breast provides 27 grams of protein, as well as minerals and B vitamins.
• Clams: A 3-ounce serving of cooked clams provides 21.8 grams of protein.
• Shrimp: A 3-ounce serving of shrimp provides 20.4 grams of protein.
• Peanuts: A 1-ounce serving of peanuts provides 7.31 grams of protein.
• Peanut butter: A 2-tablespoon serving of smooth peanut butter provides 7.2 grams of protein.

If you’re vegetarian or vegan, you’ll need to eat a variety of plant foods to meet your daily protein goal. Talk to your dietitian about how to combine plant proteins to be sure you are getting all
of the building blocks your body needs.

Choosing animal-based sources can be beneficial, as they’re considered complete proteins, meaning they contain all 9 essential amino acids. Animal-based protein sources also contain vitamins and minerals such as vitamin B12 and iron. However, some animal proteins, such as processed meats and certain cuts of meat that are high in saturated fat, can affect your health negatively. It’s best to choose leaner protein sources and cut back on red meat (e.g., pork, beef, lamb) and processed meat (i.e., meat preserved by smoking, salting, curing or adding other preservatives). Because diets high in red meat and diets high in processed meat have been linked to increased risk of colorectal cancer. If you do choose to eat red meat, choose leaner sources. Look for sources that are low in saturated fat, are unprocessed, or are high in heart-healthy unsaturated fats and omega-3 fatty acids. Some good examples are:

• White-meat poultry, such as chicken or turkey breasts
• Fish, especially fatty fish like salmon, lake trout, mackerel, herring, sardines and tuna
• Pork tenderloin
• Lean or extra-lean cuts of beef such as sirloin or round cuts, greater than 93% lean ground beef
• Eggs and egg whites
• Non-fat/low-fat Greek yogurt, cottage cheese, milk

Remember that it’s still important to eat a balanced diet that includes all food groups and a variety of both plant and animal protein sources, in addition to plenty of fruits, vegetables and whole grains. Although individual plant protein sources (e.g., beans, nuts and seeds) don’t contain all 9 essential amino acids, plant sources offer more fiber and a different variety of vitamins and minerals than animal sources of protein. And even though individual plants don’t contain all 9 essential amino acids on their own, when eaten in combination throughout the day, they do provide enough of the essential amino acids to meet your body’s needs.

To help keep fat from building up in your blood vessels, heart, and kidneys:

• Grill, broil, bake, roast, or stir-fry foods, instead of deep frying.
• Cook with nonstick cooking spray or a small amount of olive oil instead of butter.
• Trim fat from meat and remove skin from poultry before eating.
• Try to limit saturated fat and trans fat.

Heart-healthy foods include:

• Lean cuts of meat, such as loin or round
• Poultry without the skin
• Fish
• Beans
• Vegetables
• Fruits
• Low-fat or fat-free milk, yogurt, and cheese

Tips for choosing protein foods

When choosing protein foods, variety is key ²¹¹.

• Vary your protein food choices. Eat a variety of foods from the Protein Foods Group each week. Experiment with main dishes made with beans or peas, nuts, soy, and seafood.
• Choose seafood twice a week. Eat seafood in place of meat or poultry twice a week. Select a variety of seafood and include some that are higher in oils and low in mercury, such as salmon, trout, and herring.
• Make meat and poultry lean or low fat. Choose lean or low-fat cuts of meat like round or sirloin and ground beef that is at least 90% lean. Trim or drain fat from meat and remove poultry skin.
• Have an egg a day. One egg a day, on average, doesn’t increase risk for heart disease, so make eggs part of your weekly choices. Only the egg yolk contains cholesterol and saturated fat, so have as many egg whites as you want.
• Eat plant protein foods more often. Try beans and peas (kidney, pinto, black, or white beans; split peas; chickpeas; hummus), soy products (tofu, tempeh, veggie burgers), nuts, and seeds. They are naturally low in saturated fat and high in fiber.
• Choose unsalted nuts or seeds as a snack, on salads, or in main dishes to replace meat or poultry. Nuts and seeds are a concentrated source of calories, so eat small portions to keep your calories in check.
• Keep it tasty and healthy. Try grilling, broiling, roasting, or baking, they don’t add extra fat. Some lean meats need slow, moist cooking to be tender, try a slow cooker for them. Avoid breading meat or poultry, which adds extra calories.
• Make a healthy sandwich. Choose turkey, roast beef, canned tuna or salmon, or peanut butter for sandwiches. Many deli meats, such as regular bologna or salami, are high in fat, sodium and preservatives—make them occasional treats only.
• Check the Nutrition Facts label to limit salt (sodium). Salt (sodium) is added to many canned foods including beans and meats. Many processed meats such as ham, sausage, and hot dogs are high in sodium. Some fresh chicken, turkey, and pork are brined in a salt solution for flavor and tenderness.

Best protein powder for weight loss

There is no best protein powder for weight loss ⁷⁹, ⁸⁰, ⁸⁸, ⁸², ²¹², ²¹³, ⁸⁹. To lose weight you’ll need to start with finding a way to eat fewer calories than you need. A calorie is a unit of energy, which is in the foods and drinks you consume. Scientifically, the calorie (a unit of energy) was originally defined as the amount of heat required at a pressure of 1 standard atmosphere to raise the temperature of 1 gram of water 1° Celsius. When you hear something contains 100 calories, it’s a way of describing how much energy your body could get from eating or drinking it. However, since calories are too small of a measurement to use when discussing nutrition and exercise, kilocalorie (kcal) measurements are used instead and the term is interchangeable with calories. Kilocalorie (kcal) is a unit of measurement for energy that is equivalent to 1,000 calories. Also,1 kcal or 1 kilocalorie is equivalent to 1 large Calorie (with an uppercase C) or 1,000 calories.

Some countries use kilojoules (kJ) to measure how much energy people get from consuming a food or drink.

• 1 calorie = 4.184 joule
• 1 kilocalorie (kcal) = 4.184 kilojoules (kJ)
• 1 Calorie (1,000 calories) = 4.184 kilojoules (kJ)

Here’s how many calories are in your foods and drinks ²⁸:

• 1 gram of carbohydrate = 4 calories
• 1 gram of protein = 4 calories
• 1 gram of fat = 9 calories
• 1 gram of water = 0 calorie

Most foods and drinks contain calories. You can find out how many calories are in a food by looking at the nutrition facts label. The label also will describe the components of the food such as how many grams of carbohydrate, protein, and fat it contains.

That means if you know how many grams of each one are in a food, you can calculate the total calories. You would multiply the number of grams by the number of calories in a gram of that food component. For example, if a serving of potato chips (about 20 chips) has 10 grams of fat, 90 calories are from fat. That’s 10 grams x 9 calories per gram. Some foods, such as lettuce, contain few calories (1 cup of shredded lettuce has less than 10 calories). Other foods, like peanuts, contain a lot of calories (½ cup of peanuts has 427 calories).

There are many unhealthy misconceptions about weight loss. There are no magical foods or ways to combine foods that melt away excess body fat. To reduce your weight, you’ll have to reduce your calorie intake.

Calories aren’t bad for you. Your body needs calories for energy. Your body uses energy (calorie) for everything you do from breathing and sleeping to exercising. Some people mistakenly believe they have to burn off all the calories they eat or they will gain weight. This isn’t true. Your body needs some calories just to operate — to keep your heart beating and your lungs breathing. When you eat, you’re replacing the energy (calorie) you’ve used, which helps you to maintain a healthy weight. But eating more calories than your body needs and not burning enough of them off through activity can lead to weight gain and other health problems such as type 2 diabetes, heart disease, high blood pressure, certain cancers (e.g., uterine, gallbladder, kidney, liver, and colon cancers) and death ²¹⁴, ²¹⁵, ²¹⁶, ²¹⁷.

Being overweight or obese is the result of an energy imbalance between your daily energy intake and your energy expenditure resulting in excessive weight gain ²¹⁸. The amount of energy or calories you get from food and drinks (energy IN) is balanced with the energy your body uses for things like breathing, digesting, and being physically active (energy OUT):

• The same amount of energy IN and energy OUT over time = weight stays the same (Energy Balance)
• More energy IN than OUT over time = Weight Gain
• More energy OUT than IN over time = Weight Loss

In order to lose weight, energy expenditures must exceed energy intake. To lose weight, most people need to reduce the number of calories they get from food and beverages (energy IN) and increase their physical activity (energy OUT). To achieve this imbalance, you can decrease energy intake, increase energy expenditures or combine a decrease in intake with an increase in expenditures. Being physically active and eating fewer calories will help you lose weight and keep the weight off over time. As a result, most weight loss recommendations advise combining a low caloric diet with an exercise program in order to achieve a significant energy deficit ²¹⁹. A long-standing consistent observation is that regular exercise by itself is prescribed in small to moderate amounts resulting in modest weight loss or in some cases weight gain ²²⁰.

Weight loss of about 1 to 1 ½ pounds per week is considered reasonable and more likely to be maintained. For a weight loss of 1 to 1 ½ pounds per week, daily intake should be reduced by 500 to 750 calories. In general ²²¹:

• Eating plans that contain 1,200–1,500 calories each day will help most women lose weight safely.
• Eating plans that contain 1,500–1,800 calories each day are suitable for men and for women who weigh more or who exercise regularly.

Very low calorie diets of fewer than 800 calories per day should not be used unless you are being monitored by your doctor. Because dieting can be harmful because your body responds to these periods of semi-starvation by lowering its metabolic rate. When you lose weight too quickly, you lose fat and muscle. Muscle burns kilojoules, but fat doesn’t. So, when you stop dieting and return to your usual habits, your body will burn even fewer calories than before because the relative amount of muscle in your body has decreased and your metabolic rate is slower. This kind of eating pattern can also affect your general health – just one cycle of weight loss and weight gain can contribute to an increased risk of coronary heart disease (regardless of your body fat levels). That’s why it’s more important to be able to maintain weight loss.

Energy balance is also important for maintaining a healthy weight. To maintain a healthy weight, your energy IN and OUT don’t have to balance exactly every day. It’s the balance over time that helps you maintain a healthy weight.

You can reach and maintain a healthy weight if you:

• Follow a healthy diet, and if you are overweight or obese, reduce your daily intake by 500 calories for weight loss
• Are physically active
• Limit the time you spend being physically inactive

While people vary quite a bit in the amount of physical activity (exercise) they need for weight control, many can maintain their weight by doing 150 to 300 minutes (2 ½ to 5 hours) a week of moderate-intensity activity such as brisk walking. People who want to lose a large amount of weight (more than 5 percent of their body weight) and people who want to keep off the weight that they’ve lost may need to be physically active for more than 300 minutes of moderate-intensity activity each week.

You now know the basics about calories – the key to weight loss for most people is simply finding the right combination of exercise, healthy foods and cutting back on portions will help you lose those extra pounds. No fad diet required. In other words, eat healthily, watch your portions and get moving more. By losing just a few pounds with healthy eating and exercise, you’ll start to feel better. You’ll have more energy. To prevent the weight creeping back on, you need to keep going with the healthy habits you’ve formed.

How many calories do I need per day?

The total number of calories you need each day varies depends on a number of factors, namely your age, sex, height, weight, level of physical activity, and pregnancy or lactation status. According to the Dietary Guidelines for Americans, American female adult estimated calorie needs range from 1,600 to 2,400 calories per day and for males 2,000 to 3,000 calories per day ²²². The average, healthy, adult, American male consumes approximately 2,800 calories per day, and the average female about 1,800 calories ²¹⁶. But most people need different amounts of calories based on how their bodies work, how active they are and any weight management goals. And if you want to lose weight you’ll have to reduce your calorie intake.

Here is a general estimate of calories you need each day:

• Sedentary lifestyle (little to no exercise)
  • Women: 1,800 to 2,400 calories
  • Men: 2,200 to 3,000 calories
• Moderately active lifestyle (engages in moderate exercise/physical activity like walking or light yard work:
  • Women: 2,000 to 2,600 calories
  • Men: 2,400 to 2,800 calories
• Very active lifestyle (engages in hard exercise/physical activity, or has a physically demanding job):
  • Women: 2,200 to 2,800 calories
  • Men: 2,800 to 3,200 calories

These are just general guidelines. It’s essential to consult with a nutritionist or a doctor who can give personalized advice based on your specific situation. Remember, it’s not just the quantity but also the quality of calories that matters for overall health.

Obesity results from the accumulation of excessive body fat, which is stored as adipose tissue. An energy deficit of approximately 3,500 calories is required to lose one pound of fat. However, there are several factors that can influence this particular number. These include compensatory changes in your resting metabolism (basal metabolic rate [BMR]), the energy cost of work, and discretionary physical activity, which can sometimes alter this figure by 100 to 200 calories. Your basal metabolic rate (BMR) also known as resting metabolic rate (RMR) is the number of calories your body burns while performing basic life-sustaining functions, such as breathing and keeping your heart beating. Your basal metabolic rate (BMR) is typically between 1,000 and 2,000 calories per day.

How to calculate calories you need for weight loss

You can calculate your basal metabolic rate (BMR) or resting metabolic rate (RMR) using the Mifflin-St Jeor equation ²²³, which is considered more accurate than the Harris-Benedict equation, especially for lean people. According to the Academy of Nutrition and Dietetics Evidence Analysis Library (EAL), the Mifflin-St. Jeor equation accurately predicted resting metabolic rate (RMR) using actual body weight within +/- 10% of measured RMR in 70% of obese individuals ²²⁴. Of the remaining 30%, 9% were overestimations and 21% were underestimations. The individual error range was a maximum overestimate of 15% to a maximum underestimate of 20%” ²²⁵. While the Harris-Benedict and WHO equations are often used in clinical practice with reasonable accuracy, results have been mixed regarding their applications to individuals who are overweight or obese ²¹⁶.

The Mifflin-St Jeor formula for calculating your basal metabolic rate (BMR) or resting metabolic rate (RMR):

• Males Basal metabolic rate [BMR] (kcal/day) = (10 X weight in kilograms) + (6.25 X height in centimeters) – (5 X age in years) + 5 (kcal/day)
• Females Basal metabolic rate [BMR] (kcal/day) = (10 X weight in kilograms) + (6.25 X height in centimeters) – (5 X age in years) – 161 (kcal/day)

You can also use the free online Basal Metabolic Rate (BMR) calculator here: https://www.nasm.org/resources/calorie-calculator

Or the Body Weight Planner (https://www.niddk.nih.gov/health-information/weight-management/body-weight-planner).

The Body Weight Planner allows you to make personalized calorie and physical activity plans to reach a goal weight within a specific time period and to maintain it afterwards.

The Basal Metabolic Rate (BMR) calculator factor in your activity levels, overall goals, and calorie usage to help you craft a weight-loss plan.

Once you have found your basal metabolic rate (BMR), multiply your BMR by your Physical Activity Levels to provide a baseline daily caloric level for weight maintenance:

• Sedentary (light physical activity associated with typical day-to-day life) = 1
• Low Active (walking about 1.5 to 3 miles per day at 3 to 4 miles per hour, in addition to the light physical activity associated with typical day-to-day life), For males = 1.11 and females = 1.20
• Active (walking more than 3 miles per day at 3 to 4 miles per hour, in addition to light physical activity associated with typical day-to-day life: 60 minutes of at least moderate intensity physical activity). For males = 1.25 and females = 1.27
• Very Active (walking more than 7.5 miles per day at 3 to 4 miles per hour, in addition to light physical activity associated with typical day-to-day life: 60 minutes of at least moderate to vigorous intensity physical activity). For males = 1.48 and females = 1.45

Your Total Daily Energy Expenditure (TDEE) gives you the estimated number of calories you need to maintain your current weight based on your activity level.

To find your Total Daily Energy Expenditure (TDEE) multiply your Basal Metabolic Rate (BMR) by your Physical Activity Levels

For example:

• Sedentary (little to no exercise): BMR x 1
• Lightly active (walking about 1.5 to 3 miles per day at 3 to 4 miles per hour, in addition to the light physical activity associated with typical day-to-day life): BMR x For males = 1.11 and females = 1.20
• Moderately active (moderate exercise/sports 3-5 days/week): BMR x 1.55
• Very active (walking more than 7.5 miles per day at 3 to 4 miles per hour, in addition to light physical activity associated with typical day-to-day life: 60 minutes of at least moderate to vigorous intensity physical activity): BMR x For males = 1.48 and females = 1.45
• Super active (very hard exercise & physical job or 2x training): BMR x 1.9

You can increase your basal metabolic rate (BMR) by:

• Exercising more, especially interval training
• Weight training to build muscle mass
• Eating fat-burning foods
• Getting enough sleep

After calculating your basal metabolic rate (BMR) or resting metabolic rate (RMR), your RMR should be multiplied by an appropriate physical activity factor to provide your baseline daily caloric level for weight maintenance. Once your baseline caloric level is known, your recommended calorie intake should be reduced to facilitate your weight loss.

If you want to lose weight, subtract 500 to 1000 calories from your Total Daily Energy Expenditure (TDEE) to get a daily intake goal. For weight gain, add extra calories. Reducing your calorie intake by 500 calories is a common strategy to yield a weight loss of approximately one pound per week, although reductions of up to 750 calories per day are sometimes used ²²⁶.

Another approach is to reduce your current caloric intake by 30% ²²⁶. Diets that reduce caloric intake relative to energy expenditure result in weight loss, regardless of macronutrient composition ²²⁶.

Here’s how to estimate how long it will take to reach your goal:

Jessie’s current weight is 150 lbs. She wants to lose 20 lbs.

• 150lbs – 20lbs = 130lbs.
• 20lbs loss at 2lbs/week = 10 weeks.
• It will take Jessie about 10 week to lose the weight.

Remember, these are general guidelines only. It’s crucial to monitor your progress and adjust as necessary. Consulting with a nutritionist or health professional is always recommended for personalized advice.

How many calories should I eat to lose weight?

For a healthy and sustainable weight loss journey, it’s typically recommended you not to shed more than 2 pounds of fat weekly. This translates to a daily calorie deficit of 1,000 calories. It’s essential to note that when weight loss surpasses 2lbs within a week, it’s often water weight being lost, not just fat.

For those leading a more sedentary lifestyle, aiming to lose 1lb per week is a good starting point. This means creating a daily calorie deficit of 500 calories.

On the other hand, those who are more active naturally have higher daily calorie needs. So, when they’re trying to lose weight, they can afford to eat a bit more since their maintenance calories are already elevated.

For such individuals, aiming for a daily calorie deficit of 500-1,000 calories is realistic, potentially leading to a weight loss rate of up to 2lbs weekly.

What happens when your calories are too low?

Consuming calories below your body’s needs for an extended period can lead to various physiological and psychological consequences. Here’s what can happen when your caloric intake is too low:

• Slower metabolism: Your body might slow down its metabolic rate as a defense mechanism to conserve energy. This can make weight loss harder over time and weight regain more likely once normal eating resumes.
• Nutrient deficiencies: Low calorie intake can lead to inadequate intake of essential vitamins and minerals. Over time, this can result in conditions like anemia, osteoporosis, and impaired immune function.
• Loss of muscle mass: Your body might start breaking down muscle tissue for energy, especially if protein intake is inadequate. This can further slow down metabolism and lead to weakness.
• Hormonal changes: Reduced calorie intake can affect hormone levels, leading to disruptions in menstrual cycles for women, reduced bone density, and other hormonal imbalances.
• Reduced energy and fatigue: You might feel constantly tired or find it difficult to concentrate.
• Mood changes: Low caloric intake can influence mood. This can result in irritability, depression, or anxiety.
• Impaired Immune Function: Your body might become more susceptible to infections due to a weakened immune system.
• Hair and skin problems: You might experience hair loss, dry skin, or brittle nails due to inadequate nutrient intake.
• Digestive problems: Constipation or other digestive issues can occur as a result of reduced fiber and fluid intake.
• Fertility issues: Low calorie and nutrient intake can lead to fertility problems in both men and women.
• Cardiovascular problems: Chronic low calorie intake can affect heart health, leading to low blood pressure, irregular heart rhythms, or other cardiovascular issues.
• Increased risk of gallstones: Rapid weight loss from very low-calorie diets can lead to the development of gallstones.

What is the best way to lose weight?

There is no one best way to lose weight, which is why doctors and dietitians work to understand your personal circumstances when making recommendations. There is no quick fix. Improving your diet and increasing activity can be key to losing weight, although they are not the only factors that need to be considered. When aiming to lose weight it is important to have realistic goals that are achievable. Success boosts confidence in your ability to lose weight. A weight loss of between 0.5 to 2 pounds (0.5-1kg) a week is a safe and realistic target. Experts recommend losing 5 to 10 percent of your body weight within the first 6 months of treatment ²²⁷. If you weigh 200 pounds, this means losing as little as 10 pounds. Moreover, it’s not just about your weight on the scales, losing inches from your waist helps to lower your risk of conditions like type 2 diabetes and high blood pressure. To reach and stay at a healthy weight over the long term, you must focus on your overall health and lifestyle habits, not just on what you eat. Successful weight-loss programs should promote healthy behaviors that help you lose weight safely, that you can stick with every day, and that help you keep the weight off. People who successfully lose weight and keep it off develop techniques to make their new lifestyle and activity habits an enjoyable way of life and also make them life long.

You weight loss programs and weight loss maintenance programs should focus on changing your behavior to reduce energy intake by cutting unhealthy foods, decreasing sugar‐sweetened beverage consumption and fat intake, portion control, increasing fruit and vegetable intake, and adhering to a diet ²²⁸. Additionally, energy expenditure should be promoted through increasing physical activity.

American College of Sports Medicine recommendations for physical activity for Weight Loss and Prevention of Weight Regain for Adults ²²⁹:

• Maintain and improving health: 150 minutes/week
• Prevention of weight gain: 150 – 250 minutes/week
• Promote clinically significant weight loss: 225 – 420 minutes/week
• Prevention of weight gain after weight loss: 200 – 300 minutes/week

Strong evidence exists that exercise (physical activity) can reduce weight gain in those at risk for obesity, and many exercise training programs are capable of producing at least modest weight loss (~2 kg) ²²⁹. A question often encountered in the clinical setting from patients is how much exercise is needed to lose weight and what type of exercise training should be performed. Overall, the changes in weight in response to exercise training without caloric restriction are highly heterogeneous and individual differences can span weight gain to clinically significant weight loss ²³⁰. Patients should should consult their clinicians or dietitians on what are reasonable expectations based on their specific weight loss program. However, research data suggest that physical activity has an important role in the amount of weight regain following successful weight loss ²³¹. Therefore, patients attempting to reduce recidivism after weight loss should engage in physical activity levels above 200 minutes/week ²²⁹.

Furthermore, high levels of physical activity and cardiorespiratory fitness (fitness) are inversely associated with cardiovascular disease, type 2 diabetes and all-cause mortality ²³². Several epidemiological studies even suggest that high levels of physical activity or cardiorespiratory fitness reduces the health risk of obesity ²³³, ²³⁴. Moreover, cardiorespiratory fitness levels have been shown to alter the relationship of the obesity paradox, where high cardiorespiratory fitness level is associated with greater survival in all body mass index (BMI) categories ²³⁵. In summary, patients are encourage to adhere to exercise programs or engage in regular physical activity regardless of the weight loss achieved.

Another question that is often encountered in the clinical setting is if there is a difference between weight loss achieved through dietary means or through exercise training in terms of cardiovascular and type 2 diabetes mellitus risk factors. In an elegantly designed study, Ross et al. ²³⁶ randomized obese men (n= 52) to diet-induced weight loss, exercise induced weight loss, exercise without weight loss, or a control group for 3 months. The diet-induced and exercise-induced weight loss groups lost approximately 7 kg of weight (8% weight reduction), and had significant reductions in total fat mass, visceral fat and increased glucose disposal ²³⁶. However, the exercise-induced weight loss group had a greater reduction in total fat mass compared to the diet induced weight loss group ²³⁶. Importantly, the exercise-induced weight loss improved cardiorespiratory fitness (fitness) whereas the dietary group did not. In the group who performed exercise training without weight loss, the participants still experienced reductions in visceral fat and increased cardiorespiratory fitness.

The observations by Ross et al. ²³⁶ reaffirm that an exercise training program still confers health benefits to obese patients even in the absence of weight loss. Although dieting without exercise training has potential cardiovascular benefits, exercise training should be encouraged by to help patients improve cardiorespiratory fitness levels, which is an independent risk factor for cardiovascular diseases, type 2 diabetes mellitus and mortality 10, and may further augment the negative energy balance created by caloric restriction. Lastly, Ross’ observations suggest that there is a rationale for exercise training to be a part of weight loss programs as the authors observed greater changes in visceral fat, oral glucose tolerance, and glucose disposal in the exercise training group with clinically significant weight loss compared to the group with exercise without weight loss group ²³⁶.

1. LaPelusa A, Kaushik R. Physiology, Proteins. [Updated 2022 Nov 14]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK555990[↩][↩][↩][↩][↩][↩][↩][↩][↩][↩][↩][↩]
2. Cena H, Calder PC. Defining a Healthy Diet: Evidence for The Role of Contemporary Dietary Patterns in Health and Disease. Nutrients. 2020 Jan 27;12(2):334. doi: 10.3390/nu12020334[↩]
3. Wu G. Dietary protein intake and human health. Food Funct. 2016 Mar;7(3):1251-65. https://pubs.rsc.org/en/content/articlelanding/2016/fo/c5fo01530h[↩][↩]
4. Lopez MJ, Mohiuddin SS. Biochemistry, Essential Amino Acids. [Updated 2024 Apr 30]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK557845[↩][↩][↩][↩][↩][↩]
5. Morris AL, Mohiuddin SS. Biochemistry, Nutrients. [Updated 2023 May 1]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK554545[↩]
6. Protein Foods. https://www.myplate.gov/eat-healthy/protein-foods[↩][↩]
7. Pasiakos SM, Agarwal S, Lieberman HR, Fulgoni VL 3rd. Sources and Amounts of Animal, Dairy, and Plant Protein Intake of US Adults in 2007-2010. Nutrients. 2015 Aug 21;7(8):7058-69. doi: 10.3390/nu7085322[↩][↩][↩]
8. O’Neil CE, Keast DR, Fulgoni VL, Nicklas TA. Food sources of energy and nutrients among adults in the US: NHANES 2003–2006. Nutrients. 2012 Dec 19;4(12):2097-120. doi: 10.3390/nu4122097[↩][↩]
9. Dietary Guidelines for Americans. https://www.dietaryguidelines.gov/[↩][↩][↩][↩][↩]
10. Phillips S.M., Fulgoni V.L., Heaney R.P., Nicklas T.A., Slavin J.L., Weaver C.M. Commonly consumed protein foods contribute to nutrient intake, diet quality, and nutrient adequacy. Am. J. Clin. Nutr. 2015;101:1346S–1352S. doi: 10.3945/ajcn.114.084079[↩][↩][↩][↩]
11. Salome M., Huneau J.F., Le Baron C., Kesse-Guyot E., Fouillet H., Mariotti F. Substituting Meat or Dairy Products with Plant-Based Substitutes Has Small and Heterogeneous Effects on Diet Quality and Nutrient Security: A Simulation Study in French Adults (INCA3) J. Nutr. 2021;151:2435–2445. doi: 10.1093/jn/nxab146[↩][↩]
12. Hoy M.K., Murayi T., Moshfegh A.J. Effect of Animal Protein Intake on Meeting Recommendations for Nutrient Intake among US Adults, What We Eat in America, NHANES 2015–2018. Curr. Dev. Nutr. 2022;7:100027. doi: 10.1016/j.cdnut.2022.100027[↩][↩]
13. Fouillet H., Dussiot A., Perraud E., Wang J., Huneau J.F., Kesse-Guyot E., Mariotti F. Plant to animal protein ratio in the diet: Nutrient adequacy, long-term health and environmental pressure. Front. Nutr. 2023;10:1178121. doi: 10.3389/fnut.2023.1178121[↩][↩]
14. Dietary Guidelines Advisory Committee. Report of the Dietary Guidelines Advisory Committee on the Dietary Guidelines for Americans, 2010, to the Secretary of Agriculture and the Secretary of Health and Human Services. Washington (DC): US Department of Agriculture, Agricultural Research Service; 2010.[↩][↩]
15. FAO Food-Based Dietary Guidelines. 2023. https://www.fao.org/nutrition/education/food-based-dietary-guidelines[↩]
16. Cámara M, Giner RM, González-Fandos E, López-García E, Mañes J, Portillo MP, Rafecas M, Domínguez L, Martínez JA. Food-Based Dietary Guidelines around the World: A Comparative Analysis to Update AESAN Scientific Committee Dietary Recommendations. Nutrients. 2021 Sep 8;13(9):3131. doi: 10.3390/nu13093131[↩]
17. Wu G, Fanzo J, Miller DD, Pingali P, Post M, Steiner JL, Thalacker-Mercer AE. Production and supply of high-quality food protein for human consumption: sustainability, challenges, and innovations. Ann N Y Acad Sci. 2014 Aug;1321:1-19. doi: 10.1111/nyas.12500[↩]
18. Acheson KJ. Diets for body weight control and health: the potential of changing the macronutrient composition. Eur J Clin Nutr. 2013 May;67(5):462-6. doi: 10.1038/ejcn.2012.194[↩][↩][↩][↩]
19. Protein Intake for Optimal Muscle Maintenance. https://www.acsm.org/docs/default-source/files-for-resource-library/protein-intake-for-optimal-muscle-maintenance.pdf[↩][↩][↩][↩][↩][↩][↩][↩][↩][↩][↩][↩][↩][↩][↩][↩][↩][↩][↩]
20. Hector A. J., Phillips S. M. Protein recommendations for weight loss in elite athletes: a focus on body composition and performance. International Journal of Sport Nutrition and Exercise Metabolism . 2018;28(2):170–177. doi: 10.1123/ijsnem.2017-0273[↩][↩][↩][↩][↩]
21. Passariello C. L., Marchionni S., Carcuro M., et al. The Mediterranean athlete’s nutrition: are protein supplements necessary? Nutrients . 2020;12(12):p. 3681. doi: 10.3390/nu12123681[↩][↩][↩][↩]
22. Stokes T., Hector A., Morton R., McGlory C., Phillips S. Recent perspectives regarding the role of dietary protein for the promotion of muscle hypertrophy with resistance exercise training. Nutrients . 2018;10(2):p. 180. doi: 10.3390/nu10020180[↩][↩][↩][↩][↩]
23. Layman DK, Anthony TG, Rasmussen BB, Adams SH, Lynch CJ, Brinkworth GD, Davis TA. Defining meal requirements for protein to optimize metabolic roles of amino acids. Am J Clin Nutr. 2015 Jun;101(6):1330S-1338S. doi: 10.3945/ajcn.114.084053[↩][↩]
24. van Vliet S, Burd NA, van Loon LJ. The Skeletal Muscle Anabolic Response to Plant- versus Animal-Based Protein Consumption. J Nutr. 2015 Sep;145(9):1981-91. doi: 10.3945/jn.114.204305[↩]
25. Wolfe RR. The underappreciated role of muscle in health and disease. Am J Clin Nutr. 2006 Sep;84(3):475-82. doi: 10.1093/ajcn/84.3.475[↩][↩]
26. Levenhagen DK, Gresham JD, Carlson MG, Maron DJ, Borel MJ, Flakoll PJ. Postexercise nutrient intake timing in humans is critical to recovery of leg glucose and protein homeostasis. Am J Physiol Endocrinol Metab. 2001 Jun;280(6):E982-93. doi: 10.1152/ajpendo.2001.280.6.E982[↩]
27. Leenders M, Verdijk LB, van der Hoeven L, van Kranenburg J, Hartgens F, Wodzig WK, Saris WH, van Loon LJ. Prolonged leucine supplementation does not augment muscle mass or affect glycemic control in elderly type 2 diabetic men. J Nutr. 2011 Jun;141(6):1070-6. doi: 10.3945/jn.111.138495[↩]
28. Trumbo P, Schlicker S, Yates AA, Poos M; Food and Nutrition Board of the Institute of Medicine, The National Academies. Dietary reference intakes for energy, carbohydrate, fiber, fat, fatty acids, cholesterol, protein and amino acids. J Am Diet Assoc. 2002 Nov;102(11):1621-30. doi: 10.1016/s0002-8223(02)90346-9. Erratum in: J Am Diet Assoc. 2003 May;103(5):563.[↩][↩]
29. What Are Amino Acids? https://www.reagent.co.uk/blog/what-are-amino-acids/[↩]
30. What are Amino acids? https://www.jpt.com/support-contact/resources/amino-acids/[↩]
31. Biochemistry and molecular genetics. https://www.toxmsdt.com/topic-11-biochemistry.html[↩]
32. Amino Acid Analysis: Unveiling the Secrets of Protein Composition and Metabolism. https://www.creative-proteomics.com/resource/exploring-amino-acid-analysis-of-protein-composition-metabolism.htm[↩]
33. Protein. https://www.genome.gov/genetics-glossary/Protein[↩]
34. Pecoits-Filho R. Dietary protein intake and kidney disease in Western diet. Contrib Nephrol. 2007;155:102-112. doi: 10.1159/000101003[↩]
35. Kerstetter JE, O’Brien KO, Caseria DM, Wall DE, Insogna KL. The impact of dietary protein on calcium absorption and kinetic measures of bone turnover in women. J Clin Endocrinol Metab. 2005 Jan;90(1):26-31. doi: 10.1210/jc.2004-0179[↩]
36. Levine ME, Suarez JA, Brandhorst S, Balasubramanian P, Cheng CW, Madia F, Fontana L, Mirisola MG, Guevara-Aguirre J, Wan J, Passarino G, Kennedy BK, Wei M, Cohen P, Crimmins EM, Longo VD. Low protein intake is associated with a major reduction in IGF-1, cancer, and overall mortality in the 65 and younger but not older population. Cell Metab. 2014 Mar 4;19(3):407-17. doi: 10.1016/j.cmet.2014.02.006[↩][↩][↩][↩]
37. Areta J.L., Burke L.M., Ross M.L., Camera D.M., West D.W., Broad E.M., Jeacocke N.A., Moore D.R., Stellingwerff T., Phillips S.M., et al. Timing and distribution of protein ingestion during prolonged recovery from resistance exercise alters myofibrillar protein synthesis. J. Physiol. 2013;591:2319–2331. doi: 10.1113/jphysiol.2012.244897[↩][↩]
38. Cribb P.J., Williams A.D., Carey M.F., Hayes A. The effect of whey isolate and resistance training on strength, body composition, and plasma glutamine. Int. J. Sport Nutr. Exerc. Metab. 2006;16:494–509. doi: 10.1123/ijsnem.16.5.494[↩][↩]
39. Frontera WR, Ochala J. Skeletal muscle: a brief review of structure and function. Calcif Tissue Int. 2015 Mar;96(3):183-95. doi: 10.1007/s00223-014-9915-y[↩]
40. Mitchell L, Hackett D, Gifford J, Estermann F, O’Connor H. Do Bodybuilders Use Evidence-Based Nutrition Strategies to Manipulate Physique? Sports (Basel). 2017 Sep 29;5(4):76. doi: 10.3390/sports5040076[↩][↩]
41. Morton RW, McGlory C, Phillips SM. Nutritional interventions to augment resistance training-induced skeletal muscle hypertrophy. Front Physiol. (2015) 6:245. doi: 10.3389/fphys.2015.00245[↩]
42. Tarnopolsky MA, Atkinson SA, MacDougall JD, Chesley A, Phillips S, Schwarcz HP. Evaluation of protein requirements for trained strength athletes. J Appl Physiol. (1992) 73:1986–95. doi: 10.1152/jappl.1992.73.5.1986[↩]
43. Moore DR, Robinson MJ, Fry JL, Tang JE, Glover EI, Wilkinson SB, et al. Ingested protein dose response of muscle and albumin protein synthesis after resistance exercise in young men. Am J Clin Nutr. (2009) 89:161–8. doi: 10.3945/ajcn.2008.26401[↩]
44. Witard OC, Jackman SR, Breen L, Smith K, Selby A, Tipton KD. Myofibrillar muscle protein synthesis rates subsequent to a meal in response to increasing doses of whey protein at rest and after resistance exercise. Am J Clin Nutr. (2014) 99:86–95. doi: 10.3945/ajcn.112.055517[↩][↩]
45. Macnaughton LS, Wardle SL, Witard OC, McGlory C, Hamilton DL, Jeromson S, et al. The response of muscle protein synthesis following whole-body resistance exercise is greater following 40 g than 20 g of ingested whey protein. Physiol Rep. (2016) 4:e12893. doi: 10.14814/phy2.12893[↩]
46. Devries MC, Phillips SM. Supplemental protein in support of muscle mass and health: advantage whey. J Food Sci. (2015) 80(Suppl. 1):A8–15. doi: 10.1111/1750-3841.12802[↩]
47. Areta JL, Burke LM, Ross ML, Camera DM, West DW, Broad EM, et al. Timing and distribution of protein ingestion during prolonged recovery from resistance exercise alters myofibrillar protein synthesis. J Physiol. (2013) 591:2319–31. doi: 10.1113/jphysiol.2012.244897[↩]
48. Devries MC, Phillips SM. Supplemental protein in support of muscle mass and health: advantage whey. J Food Sci. 2015 Mar;80 Suppl 1:A8-A15. Doi: 10.1111/1750-3841.12802[↩][↩]
49. Spendlove J., Mitchell L., Gifford J., Hackett D., Slater G., Cobley S., O’Connor H. Dietary intake of competitive bodybuilders. Sports Med. 2015;45:1041–1063. doi: 10.1007/s40279-015-0329-4[↩][↩]
50. Devries MC, Phillips SM. Supplemental protein in support of muscle mass and health: advantage whey. J Food Sci. 2015 Mar;80 Suppl 1:A8-A15. doi: 10.1111/1750-3841.12802[↩][↩][↩]
51. Morton RW, Murphy KT, McKellar SR, Schoenfeld BJ, Henselmans M, Helms E, et al. A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. Br J Sports Med. (2018) 52:376–84. doi: 10.1136/bjsports-2017-097608[↩]
52. Finger D., Goltz F. R., Umpierre D., Meyer E., Rosa L. H. T., Schneider C. D. Effects of protein supplementation in older adults undergoing resistance training: a systematic review and meta-analysis. Sports Medicine . 2015;45(2):245–255. doi: 10.1007/s40279-014-0269-4[↩]
53. Morton R. W., Murphy K. T., McKellar S. R., et al. A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. British Journal of Sports Medicine . 2018;52(6):376–384. doi: 10.1136/bjsports-2017-097608[↩]
54. Phillips S. M., Van Loon L. J. C. Dietary protein for athletes: from requirements to optimum adaptation. Journal of Sports Sciences . 2011;29(1):S29–S38. doi: 10.1080/02640414.2011.619204[↩]
55. Porcelli S, Pugliese L, Rejc E, Pavei G, Bonato M, Montorsi M, La Torre A, Rasica L, Marzorati M. Effects of a Short-Term High-Nitrate Diet on Exercise Performance. Nutrients. 2016 Aug 31;8(9):534. doi: 10.3390/nu8090534[↩]
56. Bandara SB, Towle KM, Monnot AD. A human health risk assessment of heavy metal ingestion among consumers of protein powder supplements. Toxicol Rep. 2020 Aug 21;7:1255-1262. doi: 10.1016/j.toxrep.2020.08.001[↩]
57. Consumer Reports . Consumer Reports; Yonkers, NY: 2010. Investigation: Test Reveal Contaminants in Many Protein Drinks, Unclear Labeling May Lead to Excessive Protein Consumption Which Can Pose Health Problems. https://www.consumerreports.org/media-room/press-releases/2010/06/investigation-tests-reveal-contaminants-in-many-protein-drinks/[↩]
58. Clean Label . Clean Label Project; Broomfield, CO: 2018. 2018 Protein Powder Study. https://cleanlabelproject.org/protein-powder-infographic/[↩][↩]
59. Bernhoft R.A. Mercury toxicity and treatment: a review of the literature. J. Environ. Public Health. 2012;2012 doi: 10.1155/2012/460508[↩]
60. Godt J., Scheidig F., Grosse-Siestrup C., Esche V., Brandenburg P., Reich A., Groneberg D.A. The toxicity of cadmium and resulting hazards for human health. J. Occup. Med. Toxicol. 2006;1:22. doi: 10.1186/1745-6673-1-2[↩]
61. Needleman H. Lead poisoning. Annu. Rev. Med. 2004;55:209–222. doi: 10.1146/annurev.med.55.091902.103653[↩][↩]
62. Robles-Osorio M.L., Sabath-Silva E., Sabath E. Arsenic-mediated nephrotoxicity. Ren. Fail. 2015;37(4):542–547. doi: 10.3109/0886022X.2015.1013419[↩]
63. Vahidnia A., van der Voet G.B., de Wolff F.A. Arsenic neurotoxicity–a review. Hum. Exp. Toxicol. 2007;26(10):823–832. doi: 10.1177/0960327107084539[↩]
64. Wallace D.R., Taalab Y.M., Heinze S., Tariba Lovakovic B., Pizent A., Renieri E., Tsatsakis A., Farooqi A.A., Javorac D., Andjelkovic M., Bulat Z., Antonijevic B., Buha Djordjevic A. Toxic-metal-induced alteration in miRNA expression profile as a proposed mechanism for disease development. Cells. 2020;9(4) doi: 10.3390/cells9040901[↩]
65. Patrick L. Lead toxicity, a review of the literature. Part 1: Exposure, evaluation, and treatment. Altern Med Rev. 2006 Mar;11(1):2-22.[↩]
66. Buha A., Matovic V., Antonijevic B., Bulat Z., Curcic M., Renieri E.A., Tsatsakis A.M., Schweitzer A., Wallace D. Overview of cadmium thyroid disrupting effects and mechanisms. Int. J. Mol. Sci. 2018;19(5) doi: 10.3390/ijms19051501[↩]
67. Johri N., Jacquillet G., Unwin R. Heavy metal poisoning: the effects of cadmium on the kidney. Biometals. 2010;23(5):783–792. doi: 10.1007/s10534-010-9328-y[↩]
68. Rodriguez J., Mandalunis P.M. A review of metal exposure and its effects on bone health. J. Toxicol. 2018;2018 doi: 10.1155/2018/4854152[↩]
69. Zhou Q., Xi S. A review on arsenic carcinogenesis: epidemiology, metabolism, genotoxicity and epigenetic changes. Regul. Toxicol. Pharmacol. 2018;99:78–88. doi: 10.1016/j.yrtph.2018.09.010[↩]
70. Bellinger DC. Lead. Pediatrics. 2004 Apr;113(4 Suppl):1016-22.[↩]
71. Papanikolaou NC, Hatzidaki EG, Belivanis S, Tzanakakis GN, Tsatsakis AM. Lead toxicity update. A brief review. Med Sci Monit. 2005 Oct;11(10):RA329-36. https://medscimonit.com/abstract/index/idArt/430340[↩]
72. Zahir F., Rizwi S.J., Haq S.K., Khan R.H. Low dose mercury toxicity and human health. Environ. Toxicol. Pharmacol. 2005;20(2):351–360. doi: 10.1016/j.etap.2005.03.007[↩]
73. Swithers SE. Artificial sweeteners are not the answer to childhood obesity. Appetite. 2015 Oct;93:85-90. doi: 10.1016/j.appet.2015.03.027[↩][↩]
74. Suez J, Korem T, Zilberman-Schapira G, Segal E, Elinav E. Non-caloric artificial sweeteners and the microbiome: findings and challenges. Gut Microbes. 2015;6(2):149-55. doi: 10.1080/19490976.2015.1017700[↩][↩]
75. Pearlman M, Obert J, Casey L. The Association Between Artificial Sweeteners and Obesity. Curr Gastroenterol Rep. 2017 Nov 21;19(12):64. doi: 10.1007/s11894-017-0602-9[↩][↩]
76. Debras C, Chazelas E, Srour B, et al. Artificial sweeteners and cancer risk: Results from the NutriNet-Santé population-based cohort study. PLoS Med. 2022 Mar 24;19(3):e1003950. doi: 10.1371/journal.pmed.1003950[↩][↩]
77. Christofides EA. POINT: Artificial Sweeteners and Obesity-Not the Solution and Potentially a Problem. Endocr Pract. 2021 Oct;27(10):1052-1055. doi: 10.1016/j.eprac.2021.08.001[↩][↩]
78. Pavanello S, Moretto A, La Vecchia C, Alicandro G. Non-sugar sweeteners and cancer: Toxicological and epidemiological evidence. Regul Toxicol Pharmacol. 2023 Mar;139:105369. doi: 10.1016/j.yrtph.2023.105369[↩][↩]
79. Backx EM, Tieland M, Borgonjen-van den Berg KJ, Claessen PR, van Loon LJ, de Groot LC. Protein intake and lean body mass preservation during energy intake restriction in overweight older adults. Int J Obes (Lond). 2016 Feb;40(2):299-304. doi: 10.1038/ijo.2015.182[↩][↩]
80. Kerstetter JE, Bihuniak JD, Brindisi J, Sullivan RR, Mangano KM, Larocque S, Kotler BM, Simpson CA, Cusano AM, Gaffney-Stomberg E, Kleppinger A, Reynolds J, Dziura J, Kenny AM, Insogna KL. The Effect of a Whey Protein Supplement on Bone Mass in Older Caucasian Adults. J Clin Endocrinol Metab. 2015 Jun;100(6):2214-22. doi: 10.1210/jc.2014-3792[↩][↩]
81. Zhu K, Kerr DA, Meng X, Devine A, Solah V, Binns CW, Prince RL. Two-Year Whey Protein Supplementation Did Not Enhance Muscle Mass and Physical Function in Well-Nourished Healthy Older Postmenopausal Women. J Nutr. 2015 Nov;145(11):2520-6. doi: 10.3945/jn.115.218297[↩]
82. Smith GI, Commean PK, Reeds DN, Klein S, Mittendorfer B. Effect of Protein Supplementation During Diet-Induced Weight Loss on Muscle Mass and Strength: A Randomized Controlled Study. Obesity (Silver Spring). 2018 May;26(5):854-861. doi: 10.1002/oby.22169[↩][↩]
83. Haghighat N, Ashtary-Larky D, Bagheri R, Wong A, Cheraghloo N, Moradpour G, Nordvall M, Asbaghi O, Moeinvaziri N, Amini M, Sohrabi Z, Dutheil F. Effects of 6 Months of Soy-Enriched High Protein Compared to Eucaloric Low Protein Snack Replacement on Appetite, Dietary Intake, and Body Composition in Normal-Weight Obese Women: A Randomized Controlled Trial. Nutrients. 2021 Jun 30;13(7):2266. doi: 10.3390/nu13072266[↩]
84. Reinders I, Visser M, Jyväkorpi SK, Niskanen RT, Bosmans JE, Jornada Ben Â, Brouwer IA, Kuijper LD, Olthof MR, Pitkälä KH, Vijlbrief R, Suominen MH, Wijnhoven HAH. The cost effectiveness of personalized dietary advice to increase protein intake in older adults with lower habitual protein intake: a randomized controlled trial. Eur J Nutr. 2022 Feb;61(1):505-520. doi: 10.1007/s00394-021-02675-0. Epub 2021 Oct 5. Erratum in: Eur J Nutr. 2022 Feb;61(1):521. doi: 10.1007/s00394-021-02778-8[↩]
85. Ringholm S, Biensø RS, Kiilerich K, Guadalupe-Grau A, Aachmann-Andersen NJ, Saltin B, Plomgaard P, Lundby C, Wojtaszewski JF, Calbet JA, Pilegaard H. Bed rest reduces metabolic protein content and abolishes exercise-induced mRNA responses in human skeletal muscle. Am J Physiol Endocrinol Metab. 2011 Oct;301(4):E649-58. doi: 10.1152/ajpendo.00230.2011[↩]
86. Barone G, O’Regan J, Kelly AL, O’Mahony JA. Interactions between whey proteins and calcium salts and implications for the formulation of dairy protein-based nutritional beverage products: A review. Comprehensive Reviews in Food Science and Food Safety. 2022;21:1254–1274. doi: 10.1111/1541-4337.12884[↩]
87. Pillai AT, Morya S, Kasankala LM. Emerging Trends in Bioavailability and Pharma-Nutraceutical Potential of Whey Bioactives. J Nutr Metab. 2024 Apr 10;2024:8455666. doi: 10.1155/2024/8455666[↩][↩][↩][↩][↩][↩][↩][↩]
88. Li C, Meng H, Wu S, Fang A, Liao G, Tan X, Chen P, Wang X, Chen S, Zhu H. Daily Supplementation With Whey, Soy, or Whey-Soy Blended Protein for 6 Months Maintained Lean Muscle Mass and Physical Performance in Older Adults With Low Lean Mass. J Acad Nutr Diet. 2021 Jun;121(6):1035-1048.e6. doi: 10.1016/j.jand.2021.01.006[↩][↩]
89. Lamina T, Brandt S, Abdi HI, et al. The Effect of Protein Intake on Health: A Systematic Review [Internet]. Rockville (MD): Agency for Healthcare Research and Quality (US); 2024 Nov. 3, Results. Available from: https://www.ncbi.nlm.nih.gov/books/NBK610209[↩][↩]
90. González-Weller D., Paz-Montelongo S., Bethencourt-Barbuzano E., et al. Proteins and minerals in whey protein supplements. Foods . 2023;12(11):p. 2238. doi: 10.3390/foods12112238[↩][↩]
91. Zandona E, Blazic M, Jambrak AR. Whey utilisation: Sustainable uses and environmental approach. Food Technology and Biotechnology. 2021;59:147–161. doi: 10.17113/ftb.59.02.21.6968[↩]
92. Nicolas P, Lujan Ferreira M, Lassalle V. A review of magnetic separation of whey proteins and potential application to whey proteins recovery, isolation and utilization. Journal of Food Engineering. 2019;246:7–15. doi: 10.1016/j.jfoodeng.2018.10.021[↩]
93. Arbizu S, Chew B, Mertens-Talcott SU, Noratto G. Commercial whey products promote intestinal barrier function with glycomacropeptide enhanced activity in downregulating bacterial endotoxin lipopolysaccharides (LPS)-induced inflammationin vitro. Food & Function. 2020;11:5842–5852. doi: 10.1039/D0FO00487A[↩]
94. Anirudh J., Dhineshkumar V., Sangeetha T. Whey as crucial component in rejuvenating athlete health-a review. Journal of Postharvest Technology . 2022;10(4):135–155.[↩]
95. Corrochano A. R., Arranz E., De Noni I., et al. Intestinal health benefits of bovine whey proteins after simulated gastrointestinal digestion. Journal of Functional Foods . 2018;49:526–535. doi: 10.1016/j.jff.2018.08.043[↩]
96. Sandhu D., Morya S. A review on the comparative study of nutraceutically activated fruits and herbs-based wines. Journal of Applied and Natural Science . 2022;14(2):500–511. doi: 10.31018/jans.v14i2.3429[↩]
97. Bintsis T., Papademas P. Sustainable approaches in whey cheese production: a review. Dairy . 2023;4(2):249–270. doi: 10.3390/dairy4020018[↩]
98. Zhang L., Zhou R., Zhang J., Zhou P. Heat-induced denaturation and bioactivity changes of whey proteins. International Dairy Journal . 2021;123 doi: 10.1016/j.idairyj.2021.105175[↩]
99. Guefai F. Z., Martínez-Rodríguez A., Grindlay G., Mora J., Gras L. Elemental bioavailability in whey protein supplements. Journal of Food Composition and Analysis . 2022;112 doi: 10.1016/j.jfca.2022.104696[↩]
100. Ha H. K., Rankin S. A., Lee M. R., Lee W. J. Development and characterization of whey protein-based nano-delivery systems: a review. Molecules . 2019;24(18):p. 3254. doi: 10.3390/molecules24183254[↩]
101. Kelly P. In Whey Proteins . MA, USA: Academic Press; 2019. Manufacture of whey protein products: concentrates, isolate, whey protein fractions and microparticulated; pp. 97–122.[↩]
102. Pehlivanoğlu H., Bardakci H. F., Yaman M. Protein quality assessment of commercial whey protein supplements commonly consumed in Turkey by in vitro protein digestibility-corrected amino acid score (PDCAAS) Food Science and Technology . 2022;42 doi: 10.1590/fst.64720[↩]
103. Mehra R, Kumar H, Kumar N, Ranvir S, Jana A, Buttar HS, Telessy IG, Awuchi CG, Okpala COR, Korzeniowska M, Guiné RPF. Whey proteins processing and emergent derivatives: An insight perspective from constituents, bioactivities, functionalities to therapeutic applications. Journal of Functional Foods. 2021;87:104760. doi: 10.1016/j.jff.2021.104760[↩]
104. Meng Y, Liang Z, Zhang C, Hao S, Han H, Du P, Li A, Shao H, Li C, Liu L. Ultrasonic modification of whey protein isolate: Implications for the structural and functional properties. LWT-Food Science and Technology. 2021;152:112272. doi: 10.1016/j.lwt.2021.112272[↩]
105. Bhat, M. Y., Dar, T. A., & Singh, L. R. (2016). Casein Proteins: Structural and Functional Aspects. InTech. doi: 10.5772/64187[↩][↩]
106. Runthala A, Mbye M, Ayyash M, Xu Y, Kamal-Eldin A. Caseins: Versatility of Their Micellar Organization in Relation to the Functional and Nutritional Properties of Milk. Molecules. 2023 Feb 21;28(5):2023. doi: 10.3390/molecules28052023[↩]
107. Sodhi M., Mukesh M., Kataria R.S., Mishra B.P., Joshii B.K. Milk proteins and human health: A1/A2 milk hypothesis. Indian J. Endocrinol. Metab. 2012;16:856. doi: 10.4103/2230-8210.100685[↩]
108. Kaplan M., Baydemir B., Günar B.B., Arslan A., Duman H., Karav S. Benefits of A2 Milk for Sports Nutrition, Health and Performance. Front. Nutr. 2022;9:1500. doi: 10.3389/fnut.2022.935344[↩]
109. Roy BD. Milk: the new sports drink? a review. J Int Soc Sports Nutr. (2008) 5:15. 10.1186/1550-2783-5-15[↩][↩]
110. Ferguson-Stegall L, McCleave E, Ding Z, Doerner PG, III, Liu Y, Wang B, et al. Aerobic exercise training adaptations are increased by postexercise carbohydrate-protein supplementation. J Nutr Metab. (2011) 2011:1–11. 10.1155/2011/623182[↩]
111. Wilkinson SB, Tarnopolsky MA, MacDonald MJ, MacDonald JR, Armstrong D, Phillips SM. Consumption of fluid skim milk promotes greater muscle protein accretion after resistance exercise than does consumption of an isonitrogenous and isoenergetic soy-protein beverage. Am J Clin Nutr. (2007) 85:1031–40. 10.1093/ajcn/85.4.1031[↩]
112. Giribaldi M., Lamberti C., Cirrincione S., Giuffrida M.G., Cavallarin L. A2 milk and BCM-7 peptide as emerging parameters of milk quality. Front. Nutrition. 2022;9:65. doi: 10.3389/fnut.2022.842375[↩]
113. He M, Sun J, Jiang ZQ, Yang YX. Effects of cow’s milk beta-casein variants on symptoms of milk intolerance in Chinese adults: a multicentre, randomised controlled study. Nutr J. (2017) 16:72. 10.1186/s12937-017-0275-0[↩]
114. Çak B. Discussions of effect A1 and A2 milk beta-casein gene on health. Approaches Poult Dairy Vet Sci. (2018) 3. 10.31031/APDV.2018.03.000556[↩]
115. Ul Haq MR, Kapila R, Kapila S. Release of β-casomorphin-7/5 during simulated gastrointestinal digestion of milk β-casein variants from Indian crossbred cattle (Karan Fries). Food Chem. (2015) 168:70–9. 10.1016/j.foodchem.2014.07.024[↩]
116. Fiedorowicz E, Kaczmarski M, Cieślińska A, Sienkiewicz-Szłapka E, Jarmołowska B, Chwała B, et al. β-casomorphin-7 alters μ-opioid receptor and dipeptidyl peptidase IV genes expression in children with atopic dermatitis. Peptides. (2014) 62:144–9. 10.1016/j.peptides.2014.09.020[↩]
117. Gustavsson F, Buitenhuis AJ, Johansson M, Bertelsen HP, Glantz M, Poulsen NA, et al. Effects of breed and casein genetic variants on protein profile in milk from Swedish Red, Danish Holstein, and Danish Jersey cows. J Dairy Sci. (2014) 97:3866–77. 10.3168/jds.2013-7312[↩]
118. McLachlan CNS. beta-casein A1, ischaemic heart disease mortality, and other illnesses. Med Hypotheses. (2001) 56:262–72. 10.1054/mehy.2000.1265[↩]
119. Muehlenkamp MR, Warthesen JJ. Beta-casomorphins: analysis in cheese and susceptibility to proteolytic enzymes from Lactococcus lactis ssp. cremoris. J Dairy Sci. (1996) 79:20–6. 10.3168/jds.S0022-0302(96)76329-4[↩]
120. Jianqin S, Leiming X, Lu X, Yelland GW Ni J, Clarke AJ. Effects of milk containing only A2 beta casein versus milk containing both A1 and A2 beta casein proteins on gastrointestinal physiology, symptoms of discomfort, and cognitive behavior of people with self-reported intolerance to traditional cows’ milk. Nutr J. (2016) 15:1–16. 10.1186/s12937-016-0164-y[↩]
121. Laugesen M, Elliott R. Ischaemic heart disease, Type 1 diabetes, and cow milk A1 beta-casein. N Z Med J. 2003 Jan 24;116(1168):U295.[↩]
122. Kaminski S., Cieslinska A., Kostyra E. Polymorphism of Bovine Beta-Casein and Its Potential Effect on Human Health. J. Appl. Genet. 2007;48:189–198. doi: 10.1007/BF03195213[↩]
123. Sodhi M., Mukesh M., Kataria R.S., Mishra B.P., Joshii B.K. Milk Proteins and Human Health: A1/A2 Milk Hypothesis. Indian J. Endocrinol. Metab. 2012;16:856. doi: 10.4103/2230-8210.100685[↩]
124. Thiruvengadam M., Venkidasamy B., Thirupathi P., Chung I.-M., Subramanian U. β-Casomorphin: A Complete Health Perspective. Food Chem. 2021;337:127765. doi: 10.1016/j.foodchem.2020.127765[↩]
125. Scientific Report of EFSA prepared by a DATEX Working Group on the potential health impact of β-casomorphins and related peptides. EFSA Scientific Report (2009) 231, 1–107. https://efsa.onlinelibrary.wiley.com/doi/epdf/10.2903/j.efsa.2009.231r[↩]
126. Kaplan M, Baydemir B, Günar BB, Arslan A, Duman H, Karav S. Benefits of A2 Milk for Sports Nutrition, Health and Performance. Front Nutr. 2022 Jul 13;9:935344. doi: 10.3389/fnut.2022.935344[↩]
127. Rankin P, Lawlor MJ, Hills FA, Bell PG, Cockburn E, Lawlor M, et al. The effect of milk on recovery from repeat-sprint cycling in female team-sport athletes. Appl Physiol Nutr Metab. (2018) 43:113–22. 10.1139/apnm-2017-0275[↩]
128. Reddy PRK, Reddy AN, Ramadevi A, Kumar DS. Nutritional significance of indigenous cow milk with regard to a2 β-casein – an overview. (2016) 5:3376–80.[↩]
129. Ramakrishnan M, Eaton T, Sermet O, Savaiano D. A single meal of milk containing A2 β-casein causes fewer symptoms and lower gas production than milk containing both A1 and A2 β-casein among lactose intolerant individuals. Curr Dev Nutr. (2020) 4:772–772. 10.1093/cdn/nzaa052_041[↩]
130. Chitra P. Bovine milk: A1 and A2 beta casein milk proteins and their impact on human health: a review. Agric Rev. (2021). 10.18805/ag.R-2126[↩]
131. Lucey J.A. Advanced Dairy Chemistry. Springer; New York, NY, USA: 2016. Acid coagulation of milk; pp. 309–328.[↩]
132. Mohamed H., Johansson M., Lundh Å., Nagy P., Kamal-Eldin A. Short communication: Caseins and α-lactalbumin content of camel milk (Camelus dromedarius) determined by capillary electrophoresis. J. Dairy Sci. 2020;103:11094–11099. doi: 10.3168/jds.2020-19122[↩]
133. Dhasmana, S., Das, S., & Shrivastava, S. (2022). Potential nutraceuticals from the casein fraction of goat’s milk. Journal of Food Biochemistry, 46, e13982. https://doi.org/10.1111/jfbc.13982[↩]
134. Tvaroška I. Glycosylation Modulates the Structure and Functions of Collagen: A Review. Molecules. 2024 Mar 22;29(7):1417. doi: 10.3390/molecules29071417[↩][↩]
135. Tihanyi J., Apor P., Fekete G. Force-Velocity-Power Characteristics and Fiber Composition in Human Knee Extensor Muscles. Eur. J. Appl. Physiol. Occup. Physiol. 1982;48:331–343. doi: 10.1007/BF00430223[↩]
136. Lievens E, Klass M, Bex T, Derave W. Muscle fiber typology substantially influences time to recover from high-intensity exercise. J Appl Physiol (1985). 2020 Mar 1;128(3):648-659. doi: 10.1152/japplphysiol.00636.2019[↩]
137. Miljkovic N, Lim JY, Miljkovic I, Frontera WR. Aging of skeletal muscle fibers. Ann Rehabil Med. 2015 Apr;39(2):155-62. doi: 10.5535/arm.2015.39.2.155[↩]
138. Fast-Twitch Vs. Slow-Twitch Muscle Fiber Types + Training Tips. https://blog.nasm.org/fitness/understanding-fast-twitch-vs-slow-twitch-mucle-fibers[↩][↩][↩][↩][↩][↩][↩][↩][↩][↩]
139. Plotkin DL, Roberts MD, Haun CT, Schoenfeld BJ. Muscle Fiber Type Transitions with Exercise Training: Shifting Perspectives. Sports (Basel). 2021 Sep 10;9(9):127. doi: 10.3390/sports9090127[↩][↩][↩]
140. Tesch P.A., Karlsson J. Muscle Fiber Types and Size in Trained and Untrained Muscles of Elite Athletes. J. Appl. Physiol. (1985) 1985;59:1716–1720. doi: 10.1152/jappl.1985.59.6.1716[↩]
141. Serrano N., Colenso-Semple L.M., Lazauskus K.K., Siu J.W., Bagley J.R., Lockie R.G., Costa P.B., Galpin A.J. Extraordinary Fast-Twitch Fiber Abundance in Elite Weightlifters. PLoS ONE. 2019;14:e0207975. doi: 10.1371/journal.pone.0207975[↩]
142. Trappe S., Luden N., Minchev K., Raue U., Jemiolo B., Trappe T.A. Skeletal Muscle Signature of a Champion Sprint Runner. J. Appl. Physiol. (1985) 2015;118:1460–1466. doi: 10.1152/japplphysiol.00037.2015[↩]
143. Smerdu V., Karsch-Mizrachi I., Campione M., Leinwand L., Schiaffino S. Type IIx Myosin Heavy Chain Transcripts Are Expressed in Type IIb Fibers of Human Skeletal Muscle. Am. J. Physiol. 1994;267:C1723–C1728. doi: 10.1152/ajpcell.1994.267.6.C1723[↩]
144. Powers SK, and Howley ET. (2012). Exercise Physiology: Theory and Application to Fitness and Performance, (8th Edition). New York, NY: McGraw Hill.[↩]
145. Vanhatalo A, Poole DC, DiMenna FJ, Bailey SJ, Jones AM. Muscle fiber recruitment and the slow component of O2 uptake: constant work rate vs. all-out sprint exercise. Am J Physiol Regul Integr Comp Physiol. 2011 Mar;300(3):R700-7. doi: 10.1152/ajpregu.00761.2010[↩]
146. Trappe S, Harber M, Creer A, Gallagher P, Slivka D, Minchev K, Whitsett D. Single muscle fiber adaptations with marathon training. J Appl Physiol (1985). 2006 Sep;101(3):721-7. doi: 10.1152/japplphysiol.01595.2005[↩][↩][↩]
147. Evans WJ. Effects of exercise on senescent muscle. Clin Orthop Relat Res. 2002 Oct;(403 Suppl):S211-20. doi: 10.1097/00003086-200210001-00025[↩][↩]
148. Jones DA, Rutherford OM. Human muscle strength training: the effects of three different regimens and the nature of the resultant changes. J Physiol. 1987 Oct;391:1-11. doi: 10.1113/jphysiol.1987.sp016721[↩]
149. Shinohara M, Kouzaki M, Yoshihisa T, Fukunaga T. Efficacy of tourniquet ischemia for strength training with low resistance. Eur J Appl Physiol Occup Physiol. 1998;77(1-2):189-91. doi: 10.1007/s004210050319[↩]
150. Vandenburgh HH. Motion into mass: how does tension stimulate muscle growth? Med Sci Sports Exerc. 1987 Oct;19(5 Suppl):S142-9.[↩][↩]
151. Hill M, Goldspink G. Expression and splicing of the insulin-like growth factor gene in rodent muscle is associated with muscle satellite (stem) cell activation following local tissue damage. J Physiol. 2003 Jun 1;549(Pt 2):409-18. doi: 10.1113/jphysiol.2002.035832[↩][↩]
152. Vierck J, O’Reilly B, Hossner K, Antonio J, Byrne K, Bucci L, Dodson M. Satellite cell regulation following myotrauma caused by resistance exercise. Cell Biol Int. 2000;24(5):263-72. doi: 10.1006/cbir.2000.0499[↩][↩]
153. Allen DG, Whitehead NP, Yeung EW. Mechanisms of stretch-induced muscle damage in normal and dystrophic muscle: role of ionic changes. J Physiol. 2005 Sep 15;567(Pt 3):723-35. doi: 10.1113/jphysiol.2005.091694[↩]
154. Toigo M, Boutellier U. New fundamental resistance exercise determinants of molecular and cellular muscle adaptations. Eur J Appl Physiol. 2006 Aug;97(6):643-63. doi: 10.1007/s00421-006-0238-1[↩][↩]
155. Sinha-Hikim I, Cornford M, Gaytan H, Lee ML, Bhasin S. Effects of testosterone supplementation on skeletal muscle fiber hypertrophy and satellite cells in community-dwelling older men. J Clin Endocrinol Metab. 2006 Aug;91(8):3024-33. doi: 10.1210/jc.2006-0357[↩]
156. The Fitness Zone. https://fitness.edu.au/the-fitness-zone/muscle-hypertrophy-a-practical-guide[↩][↩][↩][↩][↩][↩]
157. Pierce JR, Clark BC, Ploutz-Snyder LL, Kanaley JA. Growth hormone and muscle function responses to skeletal muscle ischemia. J Appl Physiol (1985). 2006 Dec;101(6):1588-95. doi: 10.1152/japplphysiol.00585.2006[↩]
158. Rooney KJ, Herbert RD, Balnave RJ. Fatigue contributes to the strength training stimulus. Med Sci Sports Exerc. 1994 Sep;26(9):1160-4.[↩]
159. Schott J, McCully K, Rutherford OM. The role of metabolites in strength training. II. Short versus long isometric contractions. Eur J Appl Physiol Occup Physiol. 1995;71(4):337-41. doi: 10.1007/BF00240414[↩]
160. Smith RC, Rutherford OM. The role of metabolites in strength training. I. A comparison of eccentric and concentric contractions. Eur J Appl Physiol Occup Physiol. 1995;71(4):332-6. doi: 10.1007/BF00240413[↩]
161. Suga T, Okita K, Morita N, Yokota T, Hirabayashi K, Horiuchi M, Takada S, Takahashi T, Omokawa M, Kinugawa S, Tsutsui H. Intramuscular metabolism during low-intensity resistance exercise with blood flow restriction. J Appl Physiol (1985). 2009 Apr;106(4):1119-24. doi: 10.1152/japplphysiol.90368.2008[↩]
162. Tesch PA, Colliander EB, Kaiser P. Muscle metabolism during intense, heavy-resistance exercise. Eur J Appl Physiol Occup Physiol. 1986;55(4):362-6. doi: 10.1007/BF00422734[↩]
163. Goldspink G. Gene expression in skeletal muscle. Biochem Soc Trans. 2002 Apr;30(2):285-90.[↩]
164. Hornberger TA, Chien S. Mechanical stimuli and nutrients regulate rapamycin-sensitive signaling through distinct mechanisms in skeletal muscle. J Cell Biochem. 2006 Apr 15;97(6):1207-16. doi: 10.1002/jcb.20671[↩]
165. Schoenfeld BJ, Grgic J, Van Every DW, Plotkin DL. Loading Recommendations for Muscle Strength, Hypertrophy, and Local Endurance: A Re-Examination of the Repetition Continuum. Sports (Basel). 2021 Feb 22;9(2):32. doi: 10.3390/sports9020032[↩]
166. How Much Sleep Do You Really Need? https://www.thensf.org/how-many-hours-of-sleep-do-you-really-need[↩]
167. Kenney, W., Wilmore, J. And Costill, D. (2015) Physiology of Sport and Exercise, 6th edition. Human Kinetics: Champaign, IL.[↩]
168. Taheri S, Lin L, Austin D, Young T, Mignot E. Short sleep duration is associated with reduced leptin, elevated ghrelin, and increased body mass index. PLoS Med. 2004 Dec;1(3):e62. doi: 10.1371/journal.pmed.0010062[↩]
169. Chennaoui M, Arnal PJ, Sauvet F, Léger D. Sleep and exercise: a reciprocal issue? Sleep Med Rev. 2015 Apr;20:59-72. doi: 10.1016/j.smrv.2014.06.008[↩]
170. Bushman, Barbara A. Ph.D., FACSM. Exercise and Sleep. ACSM’s Health & Fitness Journal 17(5):p 5-8, September/October 2013. | DOI: 10.1249/FIT.0b013e3182a05fce[↩]
171. What Are the Sleep Stages? https://www.thensf.org/what-are-the-sleep-stages/[↩][↩][↩]
172. Resistance Training Recommendations to Maximize Muscle Hypertrophy in an Athletic Population: Position Stand of the IUSCA. https://journal.iusca.org/index.php/Journal/article/view/81/140[↩]
173. Booth FW, Thomason DB. Molecular and cellular adaptation of muscle in response to exercise: perspectives of various models. Physiol Rev. 1991;71(2):541–585. doi: 10.1152/physrev.1991.71.2.541[↩]
174. Ratamess NA, Alvar BA, Evetoch TK, Housh TJ, Kibler WB, Kraemer WJ. Progression models in resistance training for healthy adults. Med Sci Sports Exerc. 2009;41(3):687–708. doi: 10.1249/MSS.0b013e3181915670[↩]
175. Refalo MC, Helms ER, Robinson ZP, Hamilton DL, Fyfe JJ. Similar muscle hypertrophy following eight weeks of resistance training to momentary muscular failure or with repetitions-in-reserve in resistance-trained individuals. J Sports Sci. 2024 Jan;42(1):85-101. https://www.tandfonline.com/doi/full/10.1080/02640414.2024.2321021[↩]
176. Hickmott LM, Chilibeck PD, Shaw KA, Butcher SJ. The Effect of Load and Volume Autoregulation on Muscular Strength and Hypertrophy: A Systematic Review and Meta-Analysis. Sports Med Open. 2022 Jan 15;8(1):9. doi: 10.1186/s40798-021-00404-9[↩]
177. Refalo MC, Helms ER, Trexler ET, Hamilton DL, Fyfe JJ. Influence of Resistance Training Proximity-to-Failure on Skeletal Muscle Hypertrophy: A Systematic Review with Meta-analysis. Sports Med. 2023 Mar;53(3):649-665. doi: 10.1007/s40279-022-01784-y[↩]
178. Wackerhage H, Schoenfeld BJ, Hamilton DL, Lehti M, Hulmi JJ. Stimuli and sensors that initiate skeletal muscle hypertrophy following resistance exercise. J Appl Physiol (1985). 2019 Jan 1;126(1):30-43. doi: 10.1152/japplphysiol.00685.2018[↩]
179. Haun CT, Vann CG, Roberts BM, Vigotsky AD, Schoenfeld BJ, Roberts MD. A Critical Evaluation of the Biological Construct Skeletal Muscle Hypertrophy: Size Matters but So Does the Measurement. Front Physiol. 2019 Mar 12;10:247. doi: 10.3389/fphys.2019.00247[↩]
180. Brechue WF, Abe T. The role of FFM accumulation and skeletal muscle architecture in powerlifting performance. Eur J Appl Physiol. (2002) 86:327–36. doi: 10.1007/s00421-001-0543-7[↩]
181. Siahkouhian M, Hedayatneja M. Correlations of anthropometric and body composition variables with the performance of young elite weightlifters. J Hum Kinet. (2010) 25:125–31. doi: 10.2478/v10078-010-0040-3[↩]
182. Alway SE, MacDougall JD, Sale DG, Sutton JR, McComas AJ. Functional and structural adaptations in skeletal muscle of trained athletes. J Appl Physiol. (1988) 64:1114–20. doi: 10.1152/jappl.1988.64.3.1114[↩]
183. Hackett D.A., Johnson N.A., Chow C.M. Training practices and ergogenic aids used by male bodybuilders. J. Strength Cond. Res. 2013;27:1609–1617. doi: 10.1519/JSC.0b013e318271272a[↩]
184. Sartori, R., Romanello, V. & Sandri, M. Mechanisms of muscle atrophy and hypertrophy: implications in health and disease. Nat Commun 12, 330 (2021). https://doi.org/10.1038/s41467-020-20123-1[↩]
185. Schoenfeld, Brad J. The Mechanisms of Muscle Hypertrophy and Their Application to Resistance Training. Journal of Strength and Conditioning Research 24(10):p 2857-2872, October 2010. | DOI: 10.1519/JSC.0b013e3181e840f3[↩]
186. 15 – Therapeutic Exercise. David X. Cifu, Braddom’s Physical Medicine and Rehabilitation (Sixth Edition), Elsevier, 2021, Pages 291-315.e4, ISBN 780323625395 https://doi.org/10.1016/B978-0-323-62539-5.00015-1[↩]
187. Defining Muscular Hypertrophy & Growth Training Best Practices. https://blog.nasm.org/sports-performance/defining-muscular-hypertrophy-and-training-growth-best-practices[↩][↩][↩][↩][↩][↩]
188. The Optimum Performance Training® Model. https://www.nasm.org/certified-personal-trainer/the-opt-model[↩][↩][↩]
189. One Rep calculator. https://www.nasm.org/resources/one-rep-max-calculator[↩]
190. Institute of Medicine (US) Committee on Nutrition, Trauma, and the Brain; Erdman J, Oria M, Pillsbury L, editors. Nutrition and Traumatic Brain Injury: Improving Acute and Subacute Health Outcomes in Military Personnel. Washington (DC): National Academies Press (US); 2011. 10, Creatine. Available from: https://www.ncbi.nlm.nih.gov/books/NBK209321[↩]
191. Stricker PR. Other ergogenic agents. Clin Sports Med. 1998 Apr;17(2):283-97. doi: 10.1016/s0278-5919(05)70081-8[↩]
192. Butts J, Jacobs B, Silvis M. Creatine Use in Sports. Sports Health. 2018 Jan/Feb;10(1):31-34. doi: 10.1177/1941738117737248[↩][↩]
193. Butts J, Jacobs B, Silvis M. Creatine Use in Sports. Sports Health. 2018 Jan/Feb;10(1):31-34. Doi: 10.1177/1941738117737248[↩][↩]
194. Bird SP. Creatine supplementation and exercise performance: a brief review. J Sports Sci Med. 2003 Dec 1;2(4):123-32. https://pmc.ncbi.nlm.nih.gov/articles/PMC3963244[↩]
195. Cooke WH, Grandjean PW, Barnes WS. Effect of oral creatine supplementation on power output and fatigue during bicycle ergometry. J Appl Physiol (1985). 1995 Feb;78(2):670-3. doi: 10.1152/jappl.1995.78.2.670[↩]
196. Rawson ES, Gunn B, Clarkson PM. The effects of creatine supplementation on exercise-induced muscle damage. J Strength Cond Res. 2001 May;15(2):178-84.[↩]
197. Ellery SJ, Walker DW, Dickinson H. Creatine for women: a review of the relationship between creatine and the reproductive cycle and female-specific benefits of creatine therapy. Amino Acids. 2016 Aug;48(8):1807-17. doi: 10.1007/s00726-016-2199-y[↩]
198. Molina Juan L, Sospedra I, Perales A, González-Díaz C, Gil-Izquierdo A, Martínez-Sanz JM. Analysis of health claims regarding creatine monohydrate present in commercial communications for a sample of European sports foods supplements. Public Health Nutr. 2021 Jan 20;24(4):1-9. doi: 10.1017/S1368980020005121[↩][↩]
199. Bemben MG, Lamont HS. Creatine supplementation and exercise performance: recent findings. Sports Med. 2005;35(2):107-25. doi: 10.2165/00007256-200535020-00002[↩]
200. Branch JD. Effect of creatine supplementation on body composition and performance: a meta-analysis. Int J Sport Nutr Exerc Metab. 2003 Jun;13(2):198-226. doi: 10.1123/ijsnem.13.2.198[↩]
201. Institute of Medicine (US) Committee on Dietary Supplement Use by Military Personnel; Greenwood MRC, Oria M, editors. Use of Dietary Supplements by Military Personnel. Washington (DC): National Academies Press (US); 2008. Available from: https://www.ncbi.nlm.nih.gov/books/NBK3977[↩][↩]
202. McMorris T, Harris RC, Howard AN, Langridge G, Hall B, Corbett J, Dicks M, Hodgson C. Creatine supplementation, sleep deprivation, cortisol, melatonin and behavior. Physiol Behav. 2007 Jan 30;90(1):21-8. doi: 10.1016/j.physbeh.2006.08.024[↩]
203. Shao A, Hathcock JN. Risk assessment for creatine monohydrate. Regul Toxicol Pharmacol. 2006 Aug;45(3):242-51. doi: 10.1016/j.yrtph.2006.05.005[↩][↩]
204. Burke LM. Practical Issues in Evidence-Based Use of Performance Supplements: Supplement Interactions, Repeated Use and Individual Responses. Sports Med. 2017 Mar;47(Suppl 1):79-100. doi: 10.1007/s40279-017-0687-1[↩]
205. Rawson ES, Miles MP, Larson-Meyer DE. Dietary Supplements for Health, Adaptation, and Recovery in Athletes. Int J Sport Nutr Exerc Metab. 2018 Mar 1;28(2):188-199. doi: 10.1123/ijsnem.2017-0340[↩][↩]
206. Kreider RB, Kalman DS, Antonio J, Ziegenfuss TN, Wildman R, Collins R, Candow DG, Kleiner SM, Almada AL, Lopez HL. International Society of Sports Nutrition position stand: safety and efficacy of creatine supplementation in exercise, sport, and medicine. J Int Soc Sports Nutr. 2017 Jun 13;14:18. doi: 10.1186/s12970-017-0173-z[↩]
207. Maughan RJ, Greenhaff PL, Hespel P. Dietary supplements for athletes: emerging trends and recurring themes. J Sports Sci. 2011;29 Suppl 1:S57-66. doi: 10.1080/02640414.2011.587446[↩]
208. European Comission (2018) EU Register on Nutrition and Health Claims. Brussels: European Commission.[↩]
209. EFSA NDA Panel (EFSA Panel on Dietetic Products, Nutrition and Allergies), 2016. Scientific opinion on creatine in combination with resistance training and improvement in muscle strength: evaluation of a health claim pursuant to Article 13(5) of Regulation (EC) No 1924/2006. EFSA Journal 2016; 14(2):4400, 17 pp. doi:10.2903/j.efsa.2016.4400[↩][↩][↩][↩]
210. Roberts PA, Fox J, Peirce N, Jones SW, Casey A, Greenhaff PL. Creatine ingestion augments dietary carbohydrate mediated muscle glycogen supercompensation during the initial 24 h of recovery following prolonged exhaustive exercise in humans. Amino Acids. 2016 Aug;48(8):1831-42. doi: 10.1007/s00726-016-2252-x[↩]
211. 10 tips for choosing protein. https://jefferson.osu.edu/sites/jefferson/files/imce/Program_Pages/SNAP-Ed/DGTipsheet6ProteinFoods.pdf[↩]
212. Englert I, Bosy-Westphal A, Bischoff SC, Kohlenberg-Müller K. Impact of Protein Intake during Weight Loss on Preservation of Fat-Free Mass, Resting Energy Expenditure, and Physical Function in Overweight Postmenopausal Women: A Randomized Controlled Trial. Obes Facts. 2021;14(3):259-270. doi: 10.1159/000514427[↩]
213. Wycherley TP, Brinkworth GD, Clifton PM, Noakes M. Comparison of the effects of 52 weeks weight loss with either a high-protein or high-carbohydrate diet on body composition and cardiometabolic risk factors in overweight and obese males. Nutr Diabetes. 2012 Aug 13;2(8):e40. doi: 10.1038/nutd.2012.11[↩]
214. Adams KF, Schatzkin A, Harris TB, et al. Overweight, obesity, and mortality in a large prospective cohort of persons 50 to 71 years old. N Engl J Med. 2006;355:763–78. doi: 10.1056/NEJMoa055643[↩]
215. Field AE, Barnoya J, Colditz G. Epidemiology and health and economic consequences of obesity. In: Wadden TA, Stunkard AJ, editors. Handbook of Obesity Treatment. New York: The Guilford Press; 2002. pp. 3–18.[↩]
216. Dwyer JT, Melanson KJ, Sriprachy-anunt U, et al. Dietary Treatment of Obesity. [Updated 2015 Feb 28]. In: Feingold KR, Anawalt B, Blackman MR, et al., editors. Endotext [Internet]. South Dartmouth (MA): MDText.com, Inc.; 2000-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK278991[↩][↩][↩]
217. 2013 AHA/ACC/TOS guideline for the management of overweight and obesity in adults: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and The Obesity Society. J Am Coll Cardiol. 2014 Jul 1;63(25 Pt B):2985-3023. doi: 10.1016/j.jacc.2013.11.004. Erratum in: J Am Coll Cardiol. 2014 Jul 1;63(25 Pt B):3029-3030.[↩]
218. Thomas, D. M., Bouchard, C., Church, T., Slentz, C., Kraus, W. E., Redman, L. M., Martin, C. K., Silva, A. M., Vossen, M., Westerterp, K., & Heymsfield, S. B. (2012). Why do individuals not lose more weight from an exercise intervention at a defined dose? An energy balance analysis. Obesity reviews : an official journal of the International Association for the Study of Obesity, 13(10), 835–847. https://doi.org/10.1111/j.1467-789X.2012.01012.x[↩]
219. Aim for Healthy Weight. https://www.nhlbi.nih.gov/health/educational/lose_wt/index.htm[↩]
220. Slentz CA, Duscha BD, Johnson JL, Ketchum K, Aiken LB, Samsa GP, Houmard JA, Bales CW, Kraus WE. Effects of the amount of exercise on body weight, body composition, and measures of central obesity: STRRIDE–a randomized controlled study. Arch Intern Med. 2004 Jan 12;164(1):31-9. doi: 10.1001/archinte.164.1.31[↩]
221. Velthuis-te Wierik EJ, Westerterp KR, Van den Berg H. Effect of a moderately energy-restricted diet on energy metabolism and body composition in non-obese men. Int J Obes Relat Metab Disord. 1995;19:318–24.[↩]
222. U.S. Department of Agriculture and U.S. Department of Health and Human Services. Dietary Guidelines for Americans, 2020-2025. 9th Edition. December 2020. https://www.dietaryguidelines.gov/sites/default/files/2021-03/Dietary_Guidelines_for_Americans-2020-2025.pdf[↩]
223. Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr. 1990 Feb;51(2):241-7. doi: 10.1093/ajcn/51.2.241[↩]
224. American Dietetic Association (ADA). Adult Weight Management Guideline: Major Recommendations. ADA Evidence Analysis Library 2014. https://www.andeal.org/vault/pq132.pdf[↩]
225. Clinical Guidelines on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults–The Evidence Report. National Institutes of Health, 6: 51S-179S. https://doi.org/10.1002/j.1550-8528.1998.tb00690.x[↩]
226. American College of Cardiology/American Heart Association Task Force on Practice Guidelines, Obesity Expert Panel, 2013. Expert Panel Report: Guidelines (2013) for the management of overweight and obesity in adults. Obesity (Silver Spring). 2014 Jul;22 Suppl 2:S41-410. doi: 10.1002/oby.20660[↩][↩][↩]
227. Jensen MD, Ryan DH, Apovian CM, et al. 2013 AHA/ACC/TOS guideline for the management of overweight and obesity in adults. Circulation. 2014;129:S102–S138.[↩]
228. Varkevisser, R., van Stralen, M. M., Kroeze, W., Ket, J., & Steenhuis, I. (2019). Determinants of weight loss maintenance: a systematic review. Obesity reviews : an official journal of the International Association for the Study of Obesity, 20(2), 171–211. https://doi.org/10.1111/obr.12772[↩]
229. Donnelly JE, Blair SN, Jakicic JM, Manore MM, Rankin JW, Smith BK; American College of Sports Medicine. American College of Sports Medicine Position Stand. Appropriate physical activity intervention strategies for weight loss and prevention of weight regain for adults. Med Sci Sports Exerc. 2009 Feb;41(2):459-71. doi: 10.1249/MSS.0b013e3181949333. Erratum in: Med Sci Sports Exerc. 2009 Jul;41(7):1532.[↩][↩][↩]
230. Church TS, Martin CK, Thompson AM, Earnest CP, Mikus CR, Blair SN. Changes in weight, waist circumference and compensatory responses with different doses of exercise among sedentary, overweight postmenopausal women. PLoS One. 2009;4(2):e4515. doi: 10.1371/journal.pone.0004515[↩]
231. Swift, D. L., Johannsen, N. M., Lavie, C. J., Earnest, C. P., & Church, T. S. (2014). The role of exercise and physical activity in weight loss and maintenance. Progress in cardiovascular diseases, 56(4), 441–447. https://doi.org/10.1016/j.pcad.2013.09.012[↩]
232. Swift DL, Lavie CJ, Johannsen NM, Arena R, Earnest CP, O’Keefe JH, Milani RV, Blair SN, Church TS. Physical activity, cardiorespiratory fitness, and exercise training in primary and secondary coronary prevention. Circ J. 2013;77(2):281-92. doi: 10.1253/circj.cj-13-0007[↩]
233. Lee CD, Blair SN, Jackson AS. Cardiorespiratory fitness, body composition, and all-cause and cardiovascular disease mortality in men. Am J Clin Nutr. 1999 Mar;69(3):373-80. doi: 10.1093/ajcn/69.3.373[↩]
234. Wei M, Kampert JB, Barlow CE, Nichaman MZ, Gibbons LW, Paffenbarger RS Jr, Blair SN. Relationship between low cardiorespiratory fitness and mortality in normal-weight, overweight, and obese men. JAMA. 1999 Oct 27;282(16):1547-53. doi: 10.1001/jama.282.16.1547[↩]
235. McAuley, P. A., Kokkinos, P. F., Oliveira, R. B., Emerson, B. T., & Myers, J. N. (2010). Obesity paradox and cardiorespiratory fitness in 12,417 male veterans aged 40 to 70 years. Mayo Clinic proceedings, 85(2), 115–121. https://doi.org/10.4065/mcp.2009.0562[↩]
236. Ross R, Dagnone D, Jones PJ, Smith H, Paddags A, Hudson R, Janssen I. Reduction in obesity and related comorbid conditions after diet-induced weight loss or exercise-induced weight loss in men. A randomized, controlled trial. Ann Intern Med. 2000 Jul 18;133(2):92-103. doi: 10.7326/0003-4819-133-2-200007180-00008[↩][↩][↩][↩][↩]