Protein Requirements

November 5, 2013

There is always talk of protein and the need for it in an active population. From gym rats to athletes to the everyday person protein comes up as a required nutrient that is important for muscle growth, energy and health. Often people will look at the progress, or lack of progress they see in their training or diet and assume that it is more protein they need. With all this talk about it, advertising and “bro science” around let’s clear some things about protein up.

Protein is a term for a class of nutrients that are made up of amino acids amino acids are the basic building blocks of proteins. There are a large number of amino acids, some of which are standard and others which are non-standard, but as humans we are most concerned with 22 standard amino acids, 9 of which are considered to be essential as the human body is unable to produce them. These 9 essential amino acids need to be ingested in order for our bodies to have access to them. When amino acids are connected through chemical processes they form chains of proteins called peptides. Peptides sometimes do things in the body by themselves, but often they will combine with other peptides to form usable proteins for enzymes, structural and contractile proteins.

Protein can also be used for energy. Protein provides 4 calories (16.7 Kilojoules) per gram, fat provides 9 calories (37.7 Kilojoules) and carbohydrate provides 4 calories. As an energy source carbohydrates are broken down into simple sugars (think glucose) for our body to use, they are then either used as fuel for a variety of processes, stored as glycogen or stored as fat once the glycogen stores are full. We won’t talk about fat here as we all know about that, but protein is different. In a recent study (Bray et al 2012) found that protein did not contribute to increased fat mass in research participants.

Protein requirements are based off of an individual’s bodyweight and activity level. The recommendations are as follows:

For athletes or highly active individuals trying to lose body fat while maintaining lean mass – 1.5-2.2g/kg bodyweight (0.68-1g/lb body weight) would be your target.

For athletes or highly active individuals, or you are attempting to lose body fat while maintaining lean mass, then a daily intake of 1.0-1.5g/kg bodyweight (0.45-0.68g/lb body weight) would be appropriate.

For sedentary individuals not looking to change their body composition 0.8g/kg bodyweight (0.36g/lb body weight) and upwards would be appropriate.

For those that are obese, use your lean mass (overall weight after subtracting fat mass, which can be calculated by body fat percentage) or use your goal/target weight to calculate your protein requirements.

It is not hard to get the right amount of protein in your diet without supplementation. One example is the humble peanut butter sandwich. If you use a good whole wheat bread you can easily get in almost 20 grams of protein (5 grams per bread slice and 8 grams per serving of peanut butter). If you like eggs, 1 large egg has 6 grams or protein. Yogurt is a good source. Typically Greek yogurt has around 10 grams per serving. Lean red meats, chicken, fish are of course good sources of protein. For the non-meat and dairy eaters it gets a little more complicated to get in the right amount of protein, but legumes are a great source and so are nuts. Almonds have 20 grams of protein per cup, but there is almost 550 calories in that same serving.

Check out your diet and see what your protein intake is before you decide to buy a supplement. It may not be that you need it, but maybe you need to change your workouts or some other habit.

Useful Sources and References:

McGuire M, Beerman, KA.: Nutritional Sciences: From Fundamentals to Food. 2nd edn. Belmont, CA.: Wadsworth Cengage Learning; 2011.

Gropper S, Smith, JL., Groff, JL.: Advanced Nutrition and Human Metabolism. 5th edn. Belmont, CA.: Wadsworth Cengage Learning; 2009.

Ten Have GA, Engelen MP, Luiking YC, Deutz NE: Absorption kinetics of amino acids, peptides, and intact proteins. Int J Sport Nutr Exerc Metab 2007, 17 Suppl:S23-36.

Maljaars PW, Peters HP, Mela DJ, Masclee AA: Ileal brake: a sensible food target for appetite control. A review. Physiol Behav 2008, 95:271-281.

Bray GA, Smith SR, de Jonge L, Xie H, Rood J, Martin CK, Most M, Brock C, Mancuso S, Redman LM: Effect of dietary protein content on weight gain, energy expenditure, and body composition during overeating: a randomized controlled trial. JAMA 2012, 307:47-55.

Phillips SM. Protein requirements and supplementation in strength sports. Nutrition. (2004)

Lemon PW, Proctor DN. Protein intake and athletic performance. Sports Med. (1991)

Lemon PW. Beyond the zone: protein needs of active individuals. J Am Coll Nutr. (2000)

Tipton KD, Wolfe RR. Protein and amino acids for athletes. J Sports Sci. (2004)

Campbell B, et al. International Society of Sports Nutrition position stand: protein and exercise. J Int Soc Sports Nutr. (2007)

Rodriguez NR, DiMarco NM, Langley S; American Dietetic Association; Dietetians of Canada; American College of Sports Medicine. Position of the American Dietetic Association, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and athletic performance. J Am Diet Assoc. (2009)

Wilson J, Wilson GJ. Contemporary issues in protein requirements and consumption for resistance trained athletes. J Int Soc Sports Nutr. (2006)

Jeevanandam M, et al. Influence of increasing dietary intake on whole body protein kinetics in normal man. Clin Nutr. (1986)

Leidy HJ, et al. Higher protein intake preserves lean mass and satiety with weight loss in pre-obese and obese women. Obesity (Silver Spring). (2007)

Mettler S, Mitchell N, Tipton KD. Increased protein intake reduces lean body mass loss during weight loss in athletes. Med Sci Sports Exerc. (2010)

Layman DK, et al. Dietary protein and exercise have additive effects on body composition during weight loss in adult women. J Nutr. (2005)

Pikosky MA, et al. Increased protein maintains nitrogen balance during exercise-induced energy deficit. Med Sci Sports Exerc. (2008)

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