Thu. May 23rd, 2024

Question: Are there any studies that you know of that “prove” protein is indeed the dietary ingredient used primarily for muscle building? I have read articles where dieticians argue that the emphasis on protein in the body building industry is only a theory.
Answer: There are dozens of published studies on protein needs and protein metabolism in bodybuilders and other hard training athletes. The leading researcher in the field is Dr. Peter Lemon.
First of all, we know from nitrogen balance studies that protein foods are indeed the raw building material for muscle tissue and other body proteins. 60-70% of the body’s protein is found in muscle tissue. In order for muscle growth to occur, you must consume more protein than you utilize. All macronutrients (protein, carbohydrates and fats) contain carbon, hydrogen and oxygen, but only protein contains nitrogen. Because muscle tissue contains most of the body’s protein and protein contains nitrogen, we can study protein usage in the body by measuring the amount of nitrogen consumed versus the amount excreted (in feces, urine and sweat). If the intake of nitrogen is greater than the amount excreted, then we know that protein is being retained and new muscle is synthesized. If you excrete more nitrogen than you consume, you are in negative nitrogen balance, indicating that protein is being broken down and muscle is being lost.

Thanks to the work of Dr. Lemon and others, we now know that the RDA for protein is not adequate to maintain positive nitrogen balance in hard-training individuals and that the bodybuilders have been right all along.
The RDA’s are the official government guidelines set by the national research council. Currently the RDA for protein is based on bodyweight and is set at .8 grams per kilogram of bodyweight (that’s .36 grams per lb. of bodyweight). For a 172 lb. man that equates to a paltry 62 grams per day. it is important to note that the RDA’s were developed for the “average” sedentary person to avoid deficiency, not for athletes in hard training to gain muscle and strength. In fact, the RDA handbook even says, “no added allowance is made for stresses encountered in daily living which can give rise to increases in urinary nitrogen output.”
The current research has now proven that exercise increases protein needs. In 1986 in the journal “Medicine and Science in Sports and Exercise” (19:5, S179-S190,) Dr. Lemon says, “Several types of evidence indicate that exercise causes substantial changes in protein metabolism. In fact, recent data suggests that the protein recommended dietary allowance may actually be 100% higher for individuals who exercise on a regular basis. Optimal intakes, although unknown, may be even higher, especially for individuals attempting to increase muscle mass and strength.” Dr. Lemon’s most recent research (Nutrition Reviews, 54:S169-175,1996), indicates that strength athletes need up to 1.8g of protein per kg. of bodyweight to maintain positive nitrogen balance. That’s .8 grams per lb. of bodyweight or 140 grams a day for someone who weighs 172 lbs. This is very close to the long-held belief of bodybuilders that 1 gram per pound of bodyweight is optimal.
Some studies have shown that even higher protein intakes may be necessary in hard training strength athletes. In one study of Polish weighlifters (Nutr Metabolism 12:259-274), 5 of 10 athletes were still in negative nitrogen balance even while consuming 250% of the RDA. Although there is not enough evidence to confirm that protein intakes higher than 1.8 g/kg will increase nitrogen retention and muscle growth, there are two scenarios where it makes sense that increasing protein beyond these levels will be beneficial. The first is when weight gain is desired. To gain weight protein should be increased to allow for the caloric surplus that is necessary to add lean bodyweight. Adding more carbohydrates and fats would skew the macronutrient ratios and possibly lead to increased fat storage. The second time when more protein may be justified is when low carb dieting is being employed. In this case, protein and to some extent, fats, are increased to offset the drop in carbohydrates so that the caloric deficit does not become too large, which could result in loss of lean body mass.
So much research has been done on protein and athletes that it amazes me that so many conservative registered dieticians and medical professionals still cling to the outdated notion that the recommended daily allowance (RDA) for protein is sufficient for muscle growth. It is no longer just a theory that protein intakes higher than the RDA build muscle, it is now a scientific fact.
If you want to delve deeper into the subject, I’d suggest you head to the library and look up these studies:
1) Lemon, Peter, “Protein and Exercise: update”, Medicine and Science in Sports and Exercise, Vol 19, No. 5, Pgs S179 – S190, 1987
2) Lemon, Peter, “Is increased dietary protein necessary or beneficial for individuals with a physically active lifestyle?” Nutrition reviews, Vol 54: pgs. S 169-175, 1996
3) Lemon, Peter, “Do athletes need more dietary protein and amino acids?” International Journal of Sports Nutrition, S 39-61, 1995
4) Lemon, Peter, “Effects of exercise on protein and Amino Acid Metabolism.” Medicine and Science in Sports and Exercise, Vol.13,pgs.141-149, 1981
5) Tarnopolsky, M, Evaluation of protein requirements for trained strength athletes.” Journal of Applied Physiology, VOl 73, No 5, pgs 1986-1995, 1993
6) Tarnopolsky, M., Dietary protein requirements for bodybuilders vs sedentary controls (abstract), Medicine and Science in Sports and Exercise 18:564, 1986
7) Wagenmakers, AJM. “Muscle amino acid metabolism at rest and during exercise: role inhuman physiology and metabolism.” Exercise and Sports Science reviews, Vol.26, pgs. 287-314, 1998

Comments are closed.