Answers to your meatiest questions about protein, the key element in a bodybuilder's nutrition program.

By Jose Antonio


Protein, from the Greek word meaning "of prime importance," is a key component of the bodybuilder's nutritional program. Just as glucose serves as the building block of glycogen, amino acids serve as the building blocks of proteins. One of the most important components of your cells, protein is involved in formation of contractile tissue or muscle, it makes up a large part of the structural component of cells, it's part of enzymes, antibodies, blood . . . you name it, protein is part of it.

Even though the primary function of protein is to provide the needed amino acids to maintain an anabolic state, it may also be used as a fuel source. This usually occurs to a greater degree when you're in a carbohydrate-depleted state (for example, on a low-carb diet, exercising continuously for more than two hours). Yet what most bodybuilders want is to maintain the absolute highest levels of anabolism or muscle-building possible. The way scientists measure this is through something called nitrogen balance.

Remember that one of the components of protein is the nitrogen molecule. In fact, nitrogen makes up about 16% of protein. So when you eat protein, you're also taking in nitrogen. If you want to put on muscle, you must avoid a negative nitrogen balance, where you take in less protein than you degrade. A positive nitrogen balance exists when your protein intake exceeds protein degradation.

How Much Protein Should Bodybuilders Consume?

Talk about a controversial topic! I've met many physicians and dietitians who claim that "too much" protein is harmful. Yet Peter W.R. Lemon, PhD, a prominent expert in the field of protein and exercise research from the Applied Physiology Research Laboratory at Kent State University in Ohio, believes the hazards of eating a high-protein diet are overstated. I agree. No scientific evidence states that consuming two or even three times the Recommended Dietary Allowance (RDA) for protein is harmful for a normal, healthy and exercising individual.

Certainly, if you have damaged kidneys, then the work they need to perform to eliminate excess nitrogen would make it wise to avoid excess protein. But I haven't found any evidence that eating 1 or more grams of protein per pound of bodyweight every day has a harmful effect. In fact, in cultures where high protein intake is common, no evidence suggests that the population suffers from kidney problems. You could say the same for bodybuilders, although I'd caution that if you do consume a lot of protein, you should also drink a lot of water to avoid possible dehydration.

Suffice to say that the RDA of 0.8 grams of protein per 2.2 pounds (1 kg) of bodyweight per day is grossly inadequate for bodybuilders and athletes in general. Although muscle-protein degradation or breakdown increases during exercise, muscle-protein synthesis significantly increases for at least 24 hours after either resistance or endurance exercise. If you don't get adequate protein during this time, it would make sense that you probably won't grow or get stronger. Current research suggests that 1.5-2.0 grams of protein per 2.2 pounds of bodyweight per day is needed for those individuals interested in packing on some mass.

What Kind of Protein Should You Eat?

Basically, the protein you eat should have the entire complement of essential amino acids (they're called essential because you need to eat them; your body doesn't make them). They include branched-chains (valine, leucine, isoleucine), lysine, methionine, phenylalanine, threonine and tryptophan. Histidine is also essential for infants, and arginine for kids, who can't make it as well as adults. The body makes cysteine from methionine and tyrosine from phenylalanine, so you might say that cysteine and tyrosine are conditionally essential. Incomplete proteins, such as from peanuts, don't contain the necessary balance of all the essential amino acids.

Scientists compare the quality of protein sources through the Biological Value (BV), which measures the amount of protein retained per gram of protein absorbed. If a given protein provides all the essential amino acids in the correct proportions and is readily absorbed, its BV score will approach 100. On the other hand, if the protein is deficient in one essential amino acid, its BV score will be much lower.

Before the widespread use of whey protein, the protein sources with the highest BV (and which were used to establish the BV scale) were whole egg and human milk (BV = 100). Whey protein has a BV of about 159, even higher than whole eggs. Not only will whey protein help you put on muscle, but this stuff has potent effects on the immune system. In fact, a study by R. Kennedy, et al, found that whey protein helped stabilize or reverse tumor growth in patients with metastatic carcinoma.

When Should You Eat Protein?

The underlying mechanisms governing muscle growth aren't completely understood at this point, but we do know this: In order to experience a net growth in muscle mass, muscle anabolism must exceed muscle catabolism. That is, you need to feed your muscles with amino acids, glucose and fat to get them as big as your rottweiler. Is that why bodybuilders eat constantly? To bathe their muscle cells in an anabolic cocktail of aminos and other muscle building blocks?

On the basis of several animal studies, scientists have suggested that muscle-protein synthesis increases within 1-2 hours after exercise. In rats, just one bout of eccentric exercise has been shown to elevate total mixed and myofibrillar protein synthetic rates up to 65% for up to 41 hours.

In a recent study conducted at McMaster University in Hamilton, Ontario, Canada, J.D. MacDougall and colleagues used six resistance-trained males to examine how weight training impacts protein synthesis. Test subjects performed a "typical" bodybuilding workout and, using technology not available at your local gym, muscle-protein synthesis from the biceps brachii was determined four, 24 and 36 hours after exercise. The researchers found that muscle-protein synthesis was increased at four and 24 hours after exercise, but returned to pre-exercise levels after 36 hours following exercise.

The finding that muscle-protein synthesis is elevated for a day after exercise is important. I've heard many times that muscles grow when you aren't exercising, especially when you sleep. This is why bodybuilders eat like cows (grazers) instead of pigs (gorgers), although I've met a bodybuilder or two who were more like pigs.

But how much protein should you eat at once, and how often should you eat it? Several schools of thought exist on how much protein to eat at one sitting. Based anecdotally on what I've seen work well in many people, it seems that 30-40 grams of protein at a time is plenty. I've heard accounts of bodybuilders consuming as much as three times that amount, but I haven't seen any data indicating whether that amount is necessary or beneficial. As to how often to eat protein, I'd have to say about every three hours. Your digestive system is able to process protein relatively frequently, and keeping a steady supply on hand (or in your stomach, as the case may be) ensures that your muscles will have access to the raw materials needed to synthesize new tissue.