Table of Contents:
As with most things in nutrition, there’s no simple answer. Your individual needs will depend on your health, body composition, main goal, and level of physical activity (type, intensity, and duration). And even taking all this into account, you’ll end up with a starting number, which you’ll need to adjust through self-experimentation.
Daily requirements are expressed in grams of protein, either per kilogram of body weight (g/kg) or per pound of body weight (g/lb).
If you’re of healthy weight and sedentary, aim for 1.2–1.8 g/kg (0.54–0.82 g/lb).
If you’re of healthy weight, active, and wish to keep your weight, aim for 1.4–2.2 g/kg (0.64–1.00 g/lb). Try for the higher end of this range, as tolerated, especially if you’re an athlete.
If you’re of healthy weight, active, and wish to build muscle, aim for 1.4–3.3 g/kg (0.64–1.50 g/lb). Eating more than 2.6 g/kg (1.18 g/lb) is probably not going to lead to greater muscle gains, but it can minimize fat gains when “bulking” — i.e., when eating above maintenance in order to gain (muscle) weight.
If you’re of healthy weight, active, and wish to lose fat, aim for 2.3–3.1 g/kg (1.04–1.41 g/lb), skewing toward the higher end of this range as you become leaner or if you increase your caloric deficit (hypocaloric diet).
If you’re overweight or obese, aim for 1.2–1.5 g/kg (0.54–0.68 g/lb). You do not need to try to figure out your ideal body weight or your lean mass (aka fat-free mass). Most studies on people with obesity report their findings based on total body weight.
If you’re pregnant, aim for 1.66–1.77 g/kg (0.75–0.80 g/lb)
If you’re lactating, aim for more than 1.5 g/kg (0.68 g/lb)
If you’re vegan or obtain most of your protein from plants, than protein requirements may be higher due to the inferior protein quality (both the EAA profile and bioavailability) of plant-based proteins relative to animal-based proteins.
Also, note that …
Protein intake should be based on body weight, not on caloric intake. (But caloric intake should be based on body weight, too, so the two intakes are linked.)
Most studies have looked at dosages up to 1.5 g/kg; only a few have looked at dosages as high as 2.2–3.3 g/kg. However, even those higher dosages don’t seem to have negative effects in healthy people.
How much protein you need depends on several factors, such as your weight, your goal (weight maintenance, muscle gain, or fat loss), your being physically active or not, and whether you’re pregnant or not.
For adults, the U.S. Recommended Dietary Allowance (RDA) for protein — 0.8 g/kg — is considered the minimal amount of protein a healthy adult must consume daily to prevent muscle wasting when total caloric intake is sufficient. Notably, using a more appropriate statistical analysis of the data used to establish the RDA suggests it to be higher, at 1.0 g/kg.
Although often promoted as a goal intake level, the RDA for protein is more accurately thought of as a minimum level to prevent protein malnutrition. The RDA was determined from nitrogen balance studies, which require that people eat experimental diets for weeks before measurements are taken. This provides ample time for the body to adapt to low protein intakes by down-regulating processes that are not necessary for survival but are necessary for optimal health, such as protein turnover and immune function.
An alternative method for determining protein requirements, called the Indicator Amino Acid Oxidation (IAAO) technique, overcomes many of the shortcomings of nitrogen balance studies. For example, it allows for the assessment of protein requirements within 24 hours, thereby not allowing sufficient time for the body to adapt. Studies using the IAAO method have suggested that about 1.2 g/kg is a more appropriate RDA for healthy young men, older men, and older women.
Further evidence that the current RDA for protein is not sufficient comes from a randomized controlled trial that confined healthy, sedentary adults to a metabolic ward for eight weeks. The participants were randomized into three groups:
Each diet was equally hypercaloric: each participant consumed 40% more calories than they needed to maintain their weight. Yet, as shown in the figure below, eating near the RDA for protein resulted in loss of lean mass, and while this loss is so small as to be nonsignificant, the higher protein intakes were associated with increases in lean mass.
Another takeaway from this study is that eating more than 1.8 g/kg doesn’t seem to meaningfully benefit body composition, which makes it a good higher end for your daily protein intake, provided that you aren’t physically active or trying to lose weight.
The RDA for protein (0.8 g/kg) underestimates the needs of a healthy, sedentary adult, who should rather aim for 1.2–1.8 g/kg (0.54–0.82 g/lb).
If you’re regularly physically active, you need more protein daily than if you were sedentary. The American College of Sports Medicine, the Academy of Nutrition and Dietetics, and the Dietitians of Canada recommend 1.2–2.0 g/kg to optimize recovery from training and to promote the growth and maintenance of lean mass when caloric intake is sufficient. This recommendation is similar to that of the International Society of Sports Nutrition (1.4–2.0 g/kg).
Importantly, it may be better to aim for the higher end of the above ranges. According to the most comprehensive meta-analysis to date on the effects of protein supplementation on muscle mass and strength, the average amount of protein required to maximize lean mass is about 1.6 g/kg, and some people need upwards of 2.2 g/kg. For those interested in a comprehensive breakdown of this study, please refer to our Examine.com Research Digest, Issue 34, Volume 1.
However, only 4 of the 49 included studies were conducted in people with resistance training experience (the other 45 were in newbies). IAAO studies in athletes found different numbers: on training days, female athletes required 1.4–1.7 g/kg; the day following a regular training session, male endurance athletes required 2.1–2.7 g/kg; two days after their last resistance-training session, amateur male bodybuilders required 1.7–2.2 g/kg.
Since higher protein intakes seem to have no negative effects in healthy people, one may want to err toward the higher amounts.
Regularly active adults and athletes can optimize body composition, performance, and recovery by consuming 1.4–2.2 g/kg (0.64–1.00 g/lb) of protein — preferably aiming toward the upper end of this range.
Resistance training, such as lifting weights, is of course required for muscle gain: you can’t just feed your muscles what they need to grow; you also need to give them a reason to grow.
Assuming progressive resistance overload and a mild hypercaloric diet (370–800 kcal above maintenance), a few studies suggest you’ll gain less fat if you eat more protein (3.3 g/kg rather than 1.8–2.6 g/kg), although one did not.
What’s important to understand is that a daily protein intake of 3.3 g/kg isn’t likely to help you build more muscle than a daily protein intake of 1.8–2.6 g/kg. What the higher number can do is help you minimize the fat gains you’ll most likely experience if you eat above maintenance in order to gain (muscle) weight.
Athletes and active adults can minimize fat gain when overfeeding by increasing protein intake to upward of 3.3 g/kg (1.5 g/lb).
More protein helps preserve lean mass in dieters, especially lean dieters. An early review concluded that, to optimize body composition, dieting athletes should consume 1.8–2.7 g/kg. Later studies have argued that, to minimize lean-mass loss, dieting athletes should consume 2.3–3.1 g/kg (closer to the higher end of the range as leanness and caloric deficit increase). This latter recommendation has been upheld by the International Society of Sports Nutrition and by a review article on bodybuilding contest preparation.
Note that those recommendations are for people who are relatively lean already. Several meta-analyses involving people with overweightness or obesity suggest that 1.2–1.5 g/kg is an appropriate daily protein intake range to maximize fat loss. This range is supported by the European Association for the Study of Obesity, who recommend up to 1.5 g/kg for elderly adults with obesity. It is important to realize that this range is based on actual body weight, not on lean mass or ideal body weight.
Considering the health risks associated with overweightness and obesity, it is also noteworthy that eating a diet higher in protein (27% vs. 18% of calories) significantly reduces several cardiometabolic risk factors, including waist circumference, blood pressure, and triglycerides, while also increasing satiety. These effects are small, however, and likely dependent on the amount of body fat one loses.
When dieting for fat loss, athletes and other active adults who are already lean may maximize fat loss and muscle retention by increasing protein intake to 2.3–3.1 g/kg (1.00–1.41 g/lb). People who are overweight or obese are best served by consuming 1.2–1.5 g/kg (0.54–0.68 g/lb).
Is your whey protein working for you?
Toward the end of May, we’ll be releasing the most comprehensive and in-depth guide ever on whey protein. Add your name to the prelist and we’ll let you know as soon as The Definitive Guide to Whey Protein comes out!
Sarcopenia is defined as an impairment of physical function (walking speed or grip strength) combined with a loss of muscle mass. It is the primary cause of frailty with aging, which itself is associated with a higher risk of having disabilities that affect your ability to perform daily activities of living, having to go to a nursing home, and experiencing fractures, falls, and hospitalizations.
Collectively, the link between sarcopenia, frailty, and associated morbidities may explain why sarcopenia is associated with a greater risk of premature death and reduced quality of life. This isn’t a minor issue, either, as more than 40% of men and 55% of women over the age of 50 in the US have sarcopenia.
A low protein intake is associated with frailty and worse physical function than a higher protein intake. Aging results in anabolic resistance, a term used to describe how muscle tissue becomes less responsive to the growth-promoting effects of eating protein. Accordingly, older adults need to consume higher doses of protein in each meal to achieve maximal stimulation of muscle protein synthesis.
Although per-meal requirements for protein are higher in older adults, total daily protein requirements are similar to that of young adults. The RDA for protein for adults aged 50+ years is the same as that for younger adults, 0.8 g/kg. Like with younger adults, however, studies using the IAAO method have suggested that a more appropriate RDA is 1.2 g/kg. Several authorities now recommend older adults to consume 1.2–1.5 g/kg.
Notably, doubling protein intake from 0.8 to 1.6 g/kg has been shown to significantly increase lean body mass in elderly men. Similar observations have been made in elderly women who increase their protein intake from 0.9 to 1.4 g/kg. Even a small increase in protein intake from 1.0 to 1.3 g/kg has minor benefits towards lean mass and overall body composition.
Older adults (50+ years) should aim to consume at least 1.2–1.5 g/kg (0.54–0.68 g/lb) of protein daily.
The protein RDA for pregnant women is 1.1 g/kg. This value was estimated by adding three values:
The RDA for a healthy adult (0.8 g/kg)
The amount of additional body protein a pregnant woman accumulates
The amount of protein used by the developing fetus
However, as we saw previously with non-pregnant healthy adults, the RDA may not be sufficient, let alone optimal. There’s some evidence with the IAAO method that the RDA for pregnant women should be about 1.66 g/kg during early gestation (weeks 11–20) and 1.77 g/kg during late gestation (weeks 32–38). Moreover, a meta-analysis of 16 intervention studies reported that protein supplementation during pregnancy led to reduced risks for the baby:
34% lower risk of low gestational weight
32% lower risk of low birth weight
38% lower risk of stillbirth
This effect was more pronounced in undernourished women compared with adequately nourished women. Importantly, these values were determined from sedentary women carrying one child, meaning that pregnant women who engage in regular physical activity and/or are supporting the growth of twins may need even higher amounts.
Also, we aren’t medical doctors, and we don’t know what you could have going on with your health and pregnancy. Please be sure to consult with your OB-GYN before making any changes.
Pregnant women may require a daily protein intake of 1.7 g/kg (0.77 g/lb) to support both the fetus and themselves. Protein supplementation during pregnancy appears to lower some risks for the baby, especially in undernourished women — including the risk of stillbirth.
Like with pregnancy, there is little research investigating how lactation and breastfeeding impact protein requirements. Women produce a wide range of breast milk volumes, with no apparent meaningful effect of the women’s energy status (i.e., milk production is maintained even among women with a BMI less than 18.5). Infant demand of milk appears to be the primary regulator of how much milk is produced.
Based simply on adult protein requirements plus the protein output in breast milk, the RDA for lactating women was set at 1.3 g/kg. However, one study reported that half of lactating women consuming 1.5 g/kg of protein per day are in negative nitrogen balance, while another study suggests that consuming 1.0–1.5 g/kg of protein per day leads to a rapid down-regulation of protein turnover suggestive of an adaptive response to insufficient intakes.
Considering that there is no data investigating the effects of a protein intake greater than 1.5 g/kg in lactating women, and that consuming 1.5 g/kg or less of protein per day leads to adaptations suggestive of insufficient intake, lactating women should aim to consume at least 1.5 g/kg of protein daily.
Lactating women should aim to consume at least 1.5 g/kg of protein daily.
Is your whey protein working for you?
Toward the end of May, we’ll be releasing the most comprehensive and in-depth guide ever on whey protein. Add your name to the prelist and we’ll let you know as soon as The Definitive Guide to Whey Protein comes out!
Breast milk is considered the optimal source of nutrition for infants (0–12 months old), and is recommended to be the exclusive source of nutrition for infants up to six months of age. Using the average weight and milk intake of a healthy infant, the adequate intake level for protein for infants 0–6 months old is 1.5 g/kg.
The average protein intake for a healthy infant aged 7–12 months is estimated at 1.6 g/kg, assuming that half their protein comes from breast milk and half from complementary foods. Yet, the RDA is set at 1.2 g/kg for this age group based entirely on studies conducted in toddlers and children.
Although breast milk is considered the ideal food for infants, not all infants can breastfeed. Infant formulas provide an alternative, but there are considerable differences in composition from breast milk. One such difference is the protein content, which tends to be higher in formula.
Formula feeding is associated with greater increases in fat-free mass throughout the first year of life compared to exclusive breastfeeding. Fat mass tends to be lower during the first six months, but plays catch-up afterwards and ultimately ends up higher than that seen with breastfeeding.
The more rapid growth during the first six months of life is associated with obesity in childhood, adolescence, and young adulthood. While some have suggested that this is owed to the higher protein content of infant formula, others have argued that there are too many contributing factors to single out any one variable, not the least of which is the ability of breastfeeding to help infants develop better capabilities for self-regulating energy intake.
Moreover, if increased protein content of formula were responsible for the accelerated growth in early infancy, than how would we explain the similarities in growth between formulas containing 1.2 or 1.7 grams of protein per 100 mL, or between formulas containing 1.0, 1.3, or 1.5 grams per 100 mL? For reference, breast milk contains 1 gram of protein per 100 mL.
Still, even if consuming more protein from formula than would be obtained from breast milk is not necessarily detrimental, it doesn’t appear to confer a benefit. There is no good reason to stray from the nutrient composition of mother’s milk during infancy, unless dealing with a preterm infant.
Preterm infants need to be fed enough protein to promote growth rates similar to those observed in healthy fetuses growing in utero. Intake levels of 3.5–4.0 g/kg for infants 36 weeks’ gestational age have been recommended. Since breast milk doesn’t contain enough protein to meet these requirements, fortification is standard practice.
A systematic review by the Cochrane Collaboration reported greater weight gain and higher nitrogen accretion in preterm infants receiving 3.0–4.0 g/kg of protein, compared to lower protein intakes of Healthy infants up to 12 months of age should consume about 1.5 g/kg of protein daily during the first six months, which can be achieved with exclusive breastfeeding, and then increase their protein intake to around 3.0 g/kg during the latter six months with the use of meat as a complementary food. Preterm infants require 3.0–4.0 g/kg of protein daily to facilitate catch-up growth.
The same data used to establish the RDA for 7–12 month old infants was used to determine the RDA for toddlers aged 1–3 years, which is set at 1.05 g/kg. In the US, toddlers consume an average of 4 g/kg of protein per day, with 90% consuming more than 3 g/kg.
There is a dearth of data for this age group. However, consuming 4.0 g/kg of protein per day from meat as a complementary food led to better growth (higher length-for-age) than consuming the same amount of protein from dairy in 2-year-olds.
Toddlers in the US consume an average of 4 g/kg of protein daily, which is above their requirements based on the RDA. However, there is little research evaluating what level of protein intake is optimal. Meat appears to be a better complementary food than milk.
The RDA for protein is slightly higher in children (4–13 years) than it is for adults (0.95 g/kg), which makes sense considering that they are still growing and need more protein to facilitate the process. Like with adults, however, the RDA may underestimate true requirements.
Use of the IAAO technique in children aged 6–11 years has suggested that a more appropriate RDA is around 1.5 g/kg. Protein requirements are likely higher in children involved in sports and other athletic activities.
Unfortunately, but understandably, no long-term studies exist to determine what level of protein intake will maintain adequate health and meet the body's needs for various physiologic and metabolic functions in children. It would simply be unethical to deprive children of essential protein during such a critical life stage for development.
Children require at least 1.5 g/kg of protein daily; an unknown amount of additional protein is likely required for children that are regularly active or involved in sports.
The protein requirements discussed so far dealt with mostly omnivores and/or used animal-based protein supplements like whey and eggs. There is no reason to believe that protein requirements are inherently different in individuals following a vegan or vegetarian diet in which most protein comes from plants.
However, because plant-based sources of protein tend to be of lower quality than animal-based proteins, if you are someone who obtains most of your protein from plants, then you will need to pay attention to not just the amount of protein you eat, but also the quality of that protein.
Protein quality is determined by both a protein’s digestibility and its amino acid profile.
Digestibility matters because if you don’t digest and absorb some of the protein you eat, then it may as well have not been eaten. Compared to animal-based proteins, which consistently demonstrate a digestibility rate greater than 90%, the best plant-based sources of protein (legumes and grains) show a lower protein digestibility rate of 60–80%.
Plants contain anti-nutrients that inhibit protein digestion and absorption, such as trypsin inhibitors, phytates, and tannins. While cooking does reduce anti-nutrient concentrations, it doesn’t eliminate them completely. Turning a plant into a protein powder can, however, which is why the protein digestibility of plant protein concentrates is greater than their whole-food counterparts and similar to levels seen in animal foods.
The amino acid profile of a protein source matters because all protein, including the protein you eat and the protein in your body, is made from some combination of 20 amino acids. Our bodies can produce 11 of these, making them nonessential amino acids (NEAAs). The other nine can’t be produced by the body, making them essential amino acids (EAAs) that we must consume.
Building muscle requires that, cumulatively, muscle protein synthesis (MPS) exceeds muscle protein breakdown (MPB), resulting in a net accumulation of muscle protein. All 20 amino acids are required to build muscle tissue, but the EAAs are primarily responsible for stimulating MPS.
Regardless of whether protein comes from the whole plant or more digestible (bioavailable) plant-based protein powder, plant-based proteins contain less EAAs than animal-based proteins, which further contributes to their lower quality.
In particular, plant-based proteins are lower in the EAA leucine, which is believed to act as a signal to “turn on” MPS and anabolic signaling pathways, although all EAAs are required for the effects to persist.
The lower leucine and EAA content of plant-based proteins helps explain why several studies have reported lower rates of MPS with soy protein powders and beverages compared to whey protein, skim milk, whole milk with cheese, and lean beef.
Differences in MPS appear to translate to differences in lean mass as well, at least when modest supplemental protein doses are used (~20 grams). However, both animal-based and plant-based proteins appear to have similar effects on lean mass when used in higher doses of 33–50 grams per day, suggesting that consuming more protein overall can help offset the lower quality of the plant-based proteins.
Plant-based proteins also contain limiting amino acids, which are EAAs present in such small amounts that they bottleneck protein synthesis. Lysine is the most common limiting amino acid, especially among cereal grains like wheat and rice. Nuts and seeds also tend to have lysine as a limiting amino acid. Beans and legumes, on the other hand, contain sufficient lysine but lack sulfurous amino acids such as methionine and cysteine. Combining different plant-based proteins can help overcome these inherent deficits.
Vegans and other individuals who obtain most of their protein from plants will need to consume more protein than an omnivore to achieve similar muscle growth, because plant-based protein is less bioavailable and of lower quality.
The simplest method to overcome EAA deficits with plant-based proteins is to eat more of it. As mentioned already, a handful of studies have shown that large doses (33–50 grams per day) of rice and soy protein cause similar improvements in body composition as whey protein.
Another way to bolster the EAA profile of plant-based protein powders is to combine several sources with complementary EAA profiles. Historic examples of these complements include beans with corn in the Americas, and rice with soybean in Asia. These grain-legume combos work because legumes supply the lysine missing in grains, and grains supply the methionine and cysteine missing in legumes.
Unfortunately, most plant-based proteins are low in leucine, meaning that combining sources will not have a large benefit unless one of those sources is a freak of plant nature, like corn (whose leucine content rivals that of whey protein). A lower leucine content means that more protein needs to be eaten to maximize MPS.
Fortunately, getting around this issue is rather simple — just add leucine. Consuming a small six-gram dose of whey protein with an additional four grams of leucine has been shown to result in similar levels of MPS as consuming 25 grams of whey protein. Although data with plant proteins is not available in humans, complementary evidence does present in animal studies.
The deficits of plant-based proteins can be overcome be eating more, combining complementary proteins, and supplementing leucine to the meal.
Muscle protein synthesis (MPS) is the process of building new skeletal muscle tissue. When MPS chronically exceeds muscle protein breakdown (MPB), resulting in a positive net protein balance, we can expect muscle growth over the long term. Every time you eat represents a time to facilitate muscle growth through stimulating MPS.
Protein feeding studies using varying doses of whey protein suggest that young adults require an average of 0.24 g/kg of protein per meal to maximize MPS, with an RDA-like safe intake level to cover most young adults proposed at 0.4 g/kg. For older adults, these values are 0.4 and 0.6 g/kg, respectively.
Because these values are derived from studies using whey protein in isolation, which is especially bioavailable, rich in essential amino acids (EAAs), and rapidly digested, it is possible that higher intakes of protein are required when eating lower quality or slower digesting sources of protein (as would occur when eating a meal).
Additionally, while these values suggest a threshold for maximally stimulating MPS, there does not appear to be an upper limit for protein intake when it comes to promoting whole body protein balance. For example, consuming 70 g (0.8 g/kg) of protein from lean beef in a meal increases whole body protein synthesis and reduces whole body protein breakdown, resulting in greater net protein balance, than does 40 g (0.5 g/kg) of protein despite not further increasing MPS.
In other words, eating more protein may not necessarily translate to greater muscle-protein turnover and growth, but since muscle tissue accounts for only 25–30% of whole body protein turnover, the additional protein is not “wasted” (a common myth).
From a pragmatic perspective, it seems reasonable for adults, especially those looking to maximize muscle growth, to aim for 0.4–0.6 g/kg of protein per meal. This fits the conclusion from a recent review article on the maximal amount of protein that can be used from a single meal. The authors suggest that, to maximize lean body mass, active adults should consume 1.6–2.2 g/kg per day, spread across four meals (0.40–0.55 g/kg per meal).
For maximal stimulation of muscle protein synthesis, aim for a per-meal dose of quality protein (such as can be found in meat, eggs, and dairy) of 0.4–0.6 g/kg. Higher doses will not be wasted and are probably necessary when eating mixed meals that contain a variety of protein sources.
What do you really know about whey protein?
There are a lot of questions around whey.
How do you make sure you’re getting the right one for you? Does grass-fed matter? Cold-pressed? How do you discern quality?
Toward the end of May, we’ll be releasing the most comprehensive and in-depth guide on the topic.
Add your name to the prelist, and we’ll let you know as soon as The Definitive Guide to Whey Protein comes out!
Related Nutrition Articles
- Fact check: does glutamine build muscle?
- How can you assess protein quality?
- Whey Protein and Efficiency
- How does protein affect weight loss?
- What should you eat for weight loss?
- Is semen high in protein?
- High-Protein Diets Linked to Cancer: Should You Be Concerned?
- Can eating too much protein be bad for you?
- Are there health benefits to a low carb diet?
- How much protein do you need after exercise?
- Does high-protein intake help when dieting?
- Whey vs soy protein: which is better when losing weight?
- Does green tea inhibit nutrient uptake?
- How to minimize fat gain during the holidays
- How much protein can you eat in one sitting?
- Do muscle building supplements cause testicular cancer?
- Institute of Medicine. 10 Protein and Amino Acids . Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. (2005)
- Elango R, et al. Evidence that protein requirements have been significantly underestimated . Curr Opin Clin Nutr Metab Care. (2010)
- Young VR, Marchini JS. Mechanisms and nutritional significance of metabolic responses to altered intakes of protein and amino acids, with reference to nutritional adaptation in humans . Am J Clin Nutr. (1990)
- Elango R, Ball RO, Pencharz PB. Indicator amino acid oxidation: concept and application . J Nutr. (2008)
- Humayun MA, et al. Reevaluation of the protein requirement in young men with the indicator amino acid oxidation technique . Am J Clin Nutr. (2007)
- Rafii M, et al. Dietary Protein Requirement of Men >65 Years Old Determined by the Indicator Amino Acid Oxidation Technique Is Higher than the Current Estimated Average Requirement . J Nutr. (2016)
- Rafii M, et al. Dietary protein requirement of female adults >65 years determined by the indicator amino acid oxidation technique is higher than current recommendations . J Nutr. (2015)
- Tang M, et al. Assessment of protein requirement in octogenarian women with use of the indicator amino acid oxidation technique . Am J Clin Nutr. (2014)
- Bray GA, et al. Effect of dietary protein content on weight gain, energy expenditure, and body composition during overeating: a randomized controlled trial . JAMA. (2012)
- Thomas DT, Erdman KA, Burke LM. American College of Sports Medicine Joint Position Statement. Nutrition and Athletic Performance . Med Sci Sports Exerc. (2016)
- Jäger R, et al. International Society of Sports Nutrition Position Stand: protein and exercise . J Int Soc Sports Nutr. (2017)
- Morton RW, 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)
- Wooding DJ, et al. Increased Protein Requirements in Female Athletes after Variable-Intensity Exercise . Med Sci Sports Exerc. (2017)
- Malowany JM, et al. Protein to Maximize Whole-Body Anabolism in Resistance-trained Females after Exercise . Med Sci Sports Exerc. (2019)
- Bandegan A, et al. Indicator amino acid oxidation protein requirement estimate in endurance-trained men 24 h postexercise exceeds both the EAR and current athlete guidelines . Am J Physiol Endocrinol Metab. (2019)
- Bandegan A, et al. Indicator Amino Acid-Derived Estimate of Dietary Protein Requirement for Male Bodybuilders on a Nontraining Day Is Several-Fold Greater than the Current Recommended Dietary Allowance . J Nutr. (2017)
- Leaf A, Antonio J. The Effects of Overfeeding on Body Composition: The Role of Macronutrient Composition - A Narrative Review . Int J Exerc Sci. (2017)
- Antonio J, et al. A high protein diet (3.4 g/kg/d) combined with a heavy resistance training program improves body composition in healthy trained men and women--a follow-up investigation . J Int Soc Sports Nutr. (2015)
- Antonio J, et al. The effects of a high protein diet on indices of health and body composition--a crossover trial in resistance-trained men . J Int Soc Sports Nutr. (2016)
- Phillips SM, Van Loon LJ. Dietary protein for athletes: from requirements to optimum adaptation . J Sports Sci. (2011)
- Helms ER, et al. A systematic review of dietary protein during caloric restriction in resistance trained lean athletes: a case for higher intakes . Int J Sport Nutr Exerc Metab. (2014)
- Aragon AA, et al. International society of sports nutrition position stand: diets and body composition . J Int Soc Sports Nutr. (2017)
- Helms ER, Aragon AA, Fitschen PJ. Evidence-based recommendations for natural bodybuilding contest preparation: nutrition and supplementation . J Int Soc Sports Nutr. (2014)
- Krieger JW, et al. Effects of variation in protein and carbohydrate intake on body mass and composition during energy restriction: a meta-regression 1 . Am J Clin Nutr. (2006)
- Wycherley TP, et al. Effects of energy-restricted high-protein, low-fat compared with standard-protein, low-fat diets: a meta-analysis of randomized controlled trials . Am J Clin Nutr. (2012)
- Kim JE, et al. Effects of dietary protein intake on body composition changes after weight loss in older adults: a systematic review and meta-analysis . Nutr Rev. (2016)
- Mathus-Vliegen EM, Obesity Management Task Force of the European Association for the Study of Obesity. Prevalence, pathophysiology, health consequences and treatment options of obesity in the elderly: a guideline . Obes Facts. (2012)
- Jensen MD, et al. 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)
- Blüher M. Adipose tissue inflammation: a cause or consequence of obesity-related insulin resistance? . Clin Sci (Lond). (2016)
- Santesso N, et al. Effects of higher- versus lower-protein diets on health outcomes: a systematic review and meta-analysis . Eur J Clin Nutr. (2012)
- Cao L, Morley JE. Sarcopenia Is Recognized as an Independent Condition by an International Classification of Disease, Tenth Revision, Clinical Modification (ICD-10-CM) Code . J Am Med Dir Assoc. (2016)
- Landi F, et al. Sarcopenia as the Biological Substrate of Physical Frailty . Clin Geriatr Med. (2015)
- Kojima G. Frailty as a predictor of disabilities among community-dwelling older people: a systematic review and meta-analysis . Disabil Rehabil. (2017)
- Kojima G. Frailty as a Predictor of Nursing Home Placement Among Community-Dwelling Older Adults: A Systematic Review and Meta-analysis . J Geriatr Phys Ther. (2018)
- Kojima G. Frailty as a predictor of fractures among community-dwelling older people: A systematic review and meta-analysis . Bone. (2016)
- Cheng MH, Chang SF. Frailty as a Risk Factor for Falls Among Community Dwelling People: Evidence From a Meta-Analysis . J Nurs Scholarsh. (2017)
- Kojima G. Frailty as a predictor of hospitalisation among community-dwelling older people: a systematic review and meta-analysis . J Epidemiol Community Health. (2016)
- Brown JC, Harhay MO, Harhay MN. Sarcopenia and mortality among a population-based sample of community-dwelling older adults . J Cachexia Sarcopenia Muscle. (2016)
- Woo T, Yu S, Visvanathan R. Systematic Literature Review on the Relationship Between Biomarkers of Sarcopenia and Quality of Life in Older People . J Frailty Aging. (2016)
- Janssen I, Heymsfield SB, Ross R. Low relative skeletal muscle mass (sarcopenia) in older persons is associated with functional impairment and physical disability . J Am Geriatr Soc. (2002)
- Coelho-Júnior HJ, et al. Low Protein Intake Is Associated with Frailty in Older Adults: A Systematic Review and Meta-Analysis of Observational Studies . Nutrients. (2018)
- Coelho-Júnior HJ, et al. Relative Protein Intake and Physical Function in Older Adults: A Systematic Review and Meta-Analysis of Observational Studies . Nutrients. (2018)
- Burd NA, Gorissen SH, van Loon LJ. Anabolic resistance of muscle protein synthesis with aging . Exerc Sport Sci Rev. (2013)
- Moore DR, et al. Protein ingestion to stimulate myofibrillar protein synthesis requires greater relative protein intakes in healthy older versus younger men . J Gerontol A Biol Sci Med Sci. (2015)
- Traylor DA, Gorissen SHM, Phillips SM. Perspective: Protein Requirements and Optimal Intakes in Aging: Are We Ready to Recommend More Than the Recommended Daily Allowance? . Adv Nutr. (2018)
- Deutz NE, et al. Protein intake and exercise for optimal muscle function with aging: recommendations from the ESPEN Expert Group . Clin Nutr. (2014)
- Bauer J, et al. Evidence-based recommendations for optimal dietary protein intake in older people: a position paper from the PROT-AGE Study Group . J Am Med Dir Assoc. (2013)
- Morley JE, et al. Nutritional recommendations for the management of sarcopenia . J Am Med Dir Assoc. (2010)
- Mitchell CJ, et al. The effects of dietary protein intake on appendicular lean mass and muscle function in elderly men: a 10-wk randomized controlled trial . Am J Clin Nutr. (2017)
- Nabuco HCG, et al. Effects of Whey Protein Supplementation Pre- or Post-Resistance Training on Muscle Mass, Muscular Strength, and Functional Capacity in Pre-Conditioned Older Women: A Randomized Clinical Trial . Nutrients. (2018)
- Ten Haaf DSM, et al. Protein supplementation improves lean body mass in physically active older adults: a randomized placebo-controlled trial . J Cachexia Sarcopenia Muscle. (2019)
- Stephens TV, et al. Protein requirements of healthy pregnant women during early and late gestation are higher than current recommendations . J Nutr. (2015)
- Elango R, Ball RO. Protein and Amino Acid Requirements during Pregnancy . Adv Nutr. (2016)
- Imdad A, Bhutta ZA. Maternal nutrition and birth outcomes: effect of balanced protein-energy supplementation . Paediatr Perinat Epidemiol. (2012)
- Dewey KG. Energy and protein requirements during lactation . Annu Rev Nutr. (1997)
- Prentice AM, Goldberg GR, Prentice A. Body mass index and lactation performance . Eur J Clin Nutr. (1994)
- Daly SE, Hartmann PE. Infant demand and milk supply. Part 1: Infant demand and milk production in lactating women . J Hum Lact. (1995)
- Daly SE, Hartmann PE. Infant demand and milk supply. Part 2: The short-term control of milk synthesis in lactating women . J Hum Lact. (1995)
- Motil KJ, et al. Dietary protein and nitrogen balance in lactating and nonlactating women . Am J Clin Nutr. (1990)
- Motil KJ, et al. Whole-body protein turnover in the fed state is reduced in response to dietary protein restriction in lactating women . Am J Clin Nutr. (1996)
- Martin CR, Ling PR, Blackburn GL. Review of Infant Feeding: Key Features of Breast Milk and Infant Formula . Nutrients. (2016)
- Gale C, et al. Effect of breastfeeding compared with formula feeding on infant body composition: a systematic review and meta-analysis . Am J Clin Nutr. (2012)
- Oddy WH, et al. Early infant feeding and adiposity risk: from infancy to adulthood . Ann Nutr Metab. (2014)
- Oddy WH. Infant feeding and obesity risk in the child . Breastfeed Rev. (2012)
- Bartok CJ, Ventura AK. Mechanisms underlying the association between breastfeeding and obesity . Int J Pediatr Obes. (2009)
- Liotto N, et al. Clinical evaluation of two different protein content formulas fed to full-term healthy infants: a randomized controlled trial . BMC Pediatr. (2018)
- Oropeza-Ceja LG, et al. Lower Protein Intake Supports Normal Growth of Full-Term Infants Fed Formula: A Randomized Controlled Trial . Nutrients. (2018)
- Hay WW, Thureen P. Protein for preterm infants: how much is needed? How much is enough? How much is too much? . Pediatr Neonatol. (2010)
- Agostoni C, et al. Enteral nutrient supply for preterm infants: commentary from the European Society of Paediatric Gastroenterology, Hepatology and Nutrition Committee on Nutrition . J Pediatr Gastroenterol Nutr. (2010)
- Arslanoglu S, et al. Fortification of Human Milk for Preterm Infants: Update and Recommendations of the European Milk Bank Association (EMBA) Working Group on Human Milk Fortification . Front Pediatr. (2019)
- Ahluwalia N, et al. Usual nutrient intakes of US infants and toddlers generally meet or exceed Dietary Reference Intakes: findings from NHANES 2009-2012 . Am J Clin Nutr. (2016)
- Tang M, et al. Different Growth Patterns Persist at 24 Months of Age in Formula-Fed Infants Randomized to Consume a Meat- or Dairy-Based Complementary Diet from 5 to 12 Months of Age . J Pediatr. (2019)
- Elango R, et al. Protein requirement of healthy school-age children determined by the indicator amino acid oxidation method . Am J Clin Nutr. (2011)
- Rodriguez NR. Optimal quantity and composition of protein for growing children . J Am Coll Nutr. (2005)
- Rogerson D. Vegan diets: practical advice for athletes and exercisers . J Int Soc Sports Nutr. (2017)
- Moughan P, et al. The assessment of amino acid digestibility in foods for humans and including a collation of published ileal amino acid digestibility data for human foods . FAO. (2011)
- Sarwar Gilani G, Wu Xiao C, Cockell KA. Impact of antinutritional factors in food proteins on the digestibility of protein and the bioavailability of amino acids and on protein quality . Br J Nutr. (2012)
- Hou Y, Yin Y, Wu G. Dietary essentiality of "nutritionally non-essential amino acids" for animals and humans . Exp Biol Med (Maywood). (2015)
- Volpi E, et al. Essential amino acids are primarily responsible for the amino acid stimulation of muscle protein anabolism in healthy elderly adults . Am J Clin Nutr. (2003)
- Wilkinson DJ, et al. Effects of leucine and its metabolite β-hydroxy-β-methylbutyrate on human skeletal muscle protein metabolism . J Physiol. (2013)
- Devries MC, et al. Leucine, Not Total Protein, Content of a Supplement Is the Primary Determinant of Muscle Protein Anabolic Responses in Healthy Older Women . J Nutr. (2018)
- Wolfe RR. Branched-chain amino acids and muscle protein synthesis in humans: myth or reality? . J Int Soc Sports Nutr. (2017)
- Yang Y, et al. Myofibrillar protein synthesis following ingestion of soy protein isolate at rest and after resistance exercise in elderly men . Nutr Metab (Lond). (2012)
- Mitchell CJ, et al. Soy protein ingestion results in less prolonged p70S6 kinase phosphorylation compared to whey protein after resistance exercise in older men . J Int Soc Sports Nutr. (2015)
- Wilkinson SB, et al. 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)
- Gran P, et al. Muscle p70S6K phosphorylation in response to soy and dairy rich meals in middle aged men with metabolic syndrome: a randomised crossover trial . Nutr Metab (Lond). (2014)
- Phillips SM. Nutrient-rich meat proteins in offsetting age-related muscle loss . Meat Sci. (2012)
- Volek JS, et al. Whey protein supplementation during resistance training augments lean body mass . J Am Coll Nutr. (2013)
- Hartman JW, et al. Consumption of fat-free fluid milk after resistance exercise promotes greater lean mass accretion than does consumption of soy or carbohydrate in young, novice, male weightlifters . Am J Clin Nutr. (2007)
- Joy JM, et al. The effects of 8 weeks of whey or rice protein supplementation on body composition and exercise performance . Nutr J. (2013)
- Kalman D, et al. Effect of protein source and resistance training on body composition and sex hormones . J Int Soc Sports Nutr. (2007)
- Brown EC, et al. Soy versus whey protein bars: effects on exercise training impact on lean body mass and antioxidant status . Nutr J. (2004)
- Mobley CB, et al. Effects of Whey, Soy or Leucine Supplementation with 12 Weeks of Resistance Training on Strength, Body Composition, and Skeletal Muscle and Adipose Tissue Histological Attributes in College-Aged Males . Nutrients. (2017)
- Young VR, Pellett PL. Plant proteins in relation to human protein and amino acid nutrition . Am J Clin Nutr. (1994)
- Woolf PJ, Fu LL, Basu A. vProtein: identifying optimal amino acid complements from plant-based foods . PLoS One. (2011)
- Churchward-Venne TA, et al. Leucine supplementation of a low-protein mixed macronutrient beverage enhances myofibrillar protein synthesis in young men: a double-blind, randomized trial . Am J Clin Nutr. (2014)
- Norton LE, et al. Leucine content of dietary proteins is a determinant of postprandial skeletal muscle protein synthesis in adult rats . Nutr Metab (Lond). (2012)
- Brook MS, et al. Skeletal muscle hypertrophy adaptations predominate in the early stages of resistance exercise training, matching deuterium oxide-derived measures of muscle protein synthesis and mechanistic target of rapamycin complex 1 signaling . FASEB J. (2015)
- Damas F, et al. Resistance training-induced changes in integrated myofibrillar protein synthesis are related to hypertrophy only after attenuation of muscle damage . J Physiol. (2016)
- Morton RW, McGlory C, Phillips SM. Nutritional interventions to augment resistance training-induced skeletal muscle hypertrophy . Front Physiol. (2015)
- Deutz NE, Wolfe RR. Is there a maximal anabolic response to protein intake with a meal? . Clin Nutr. (2013)
- Kim IY, et al. The anabolic response to a meal containing different amounts of protein is not limited by the maximal stimulation of protein synthesis in healthy young adults . Am J Physiol Endocrinol Metab. (2016)
- Nair KS, Halliday D, Griggs RC. Leucine incorporation into mixed skeletal muscle protein in humans . Am J Physiol. (1988)
- Schoenfeld BJ, Aragon AA. How much protein can the body use in a single meal for muscle-building? Implications for daily protein distribution . J Int Soc Sports Nutr. (2018)