Extra Protein Does Not Enlarge Muscles

A new review of 15 studies shows that protein supplementation offered no added benefit for older weight lifters (J Am Med Dir Assoc, Oct 1, 2016;17(10):959). Just eating extra protein does not enlarge muscles, despite the claims made for protein supplements and high-protein diets (Clin Interv Aging, July, 2012 ;7:225 - 234). You cannot prevent muscle loss at any age just by eating extra protein (J. Nutr, June 11, 2014).

Older people who lifted weights gained no additional muscle strength or size from taking extra protein (Sports Med, Feb 2015;45(2):245-55). Eating large amounts of high-protein foods did not decrease loss of muscle size or strength in men who had a cast put on an arm or leg for five days (The Journal of Nutrition, June 26, 2014). However, you do need protein to make muscles larger and stronger and it takes more protein to make muscles stronger in older people than in younger people (FASEB J, 2005; 19 (3): 422–4 and Am. J. Physiol Endocrinol Metab, 2006; 291 (2): E381–7). You can get plenty of protein to meet these needs from ordinary foods. See How Much Protein Do You Need and Muscles and Diet

Taking sources of protein and sugar shortly after lifting weights increases muscle growth (ACSM's Health & Fitness Journal, March/April 2013;17(2):10–15). Sugar can enter a resting muscle only when insulin drives it into that muscle. On the other hand, contracting muscles can draw sugar from the bloodstream without needing insulin, and during exercise, muscles are incredibly sensitive to insulin. This increased sensitivity to insulin is maximal during exercise and for up to an hour after you finish exercising, and then declines rapidly until it is gone completely in about 17 hours.

Insulin drives amino acids, the building blocks for protein, as well as sugar into muscles. Amino acids are necessary for muscle healing and any increase in the passage of amino acids into muscle helps muscles heal faster. Any combination of foods that contain sugar and protein will hasten muscle healing. All fruits contain sugar, while protein is found in all beans, nuts and other seeds and virtually all animal products such as fish, eggs, dairy products, meat and poultry, so you can meet your needs with any combinations of these foods that you like. 

Get our newsletter