A review of 49 studies on a total of 1800 weightlifters, who lifted at least twice a week for at least six weeks, found that doubling the recommended Dietary Allowance (RDA) of protein increased strength gains by nine percent and added about a pound of muscle (British Journal of Sports Medicine, Mar 1,2018;52(6):376-384). With aging, the extra protein offered less muscle growth. The authors found no difference between different sources of protein or whether the extra protein came from food or supplements. They wrote that going to the gym and doing resistance exercise is what makes muscles grow, not taking large amounts of protein from any source.
You need more protein than usual when you are trying to make your muscles larger, but taking in more than twice the RDA for protein causes no additional muscle growth. The recommended daily requirement for the average person is 0.4 grams of protein per pound of body weight. The additional gains in muscle strength from taking extra protein leveled off at 0.7 grams per pound of body weight. Thus when you are doing resistance exercises to grow larger muscles, you need to take in up to twice the RDA for protein and you do not need more protein than that. You can easily accomplish this just by eating more food.
Extra Protein for Older Lifters?
An earlier review of 15 studies showed 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 (Clin Interv Aging, July, 2012 ;7:225 – 234). Another study showed that taking extra protein doesn’t even increase muscle strength in men taking weekly injections of 100 mg of testosterone (JAMA Internal Medicine, April, 2018). You cannot prevent muscle loss at any age just by eating extra protein (J Nutr, June 11, 2014). 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 (J Nutr, June 26, 2014).
Taking sources of protein and sugar shortly after lifting weights may hasten healing and help to increase muscle growth (ACSM 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.
My Recommendations
• Almost everyone will lose muscle size and strength with aging.
• You can slow down loss of strength with aging by doing resistance exercises regularly.
• You can gain maximum muscle-building benefits from your weight lifting program by eating about double the recommended daily requirement for protein (0.4 grams per pound of body weight, or about 50 to 70 grams per day).
• Taking in large amounts of protein from food or supplements has not been shown to cause additional muscle growth.
Making Muscles Stronger
Exercise for Endurance AND Strength
Checked 2/13/23
