[Adam F]

Vegetarian diets are plant based, thus the quality of ingested protein may be questioned. A sufficient amount of amino acids can be supplied by plant foods alone, if a variety of foods are consumed, and eaten together, and energy intake is sufficient. My comment: As an example, when grains are eaten with legumes, the protein becomes non-limiting. Grains are low in lysine but high in methionine while legumes are low in methionine but high in lysine. This method is often termed protein combining. A big concern, are individuals who avoid all animal protein sources (vegans). There is a good chance if diet is too restricted as with many vegans numerous micronutrient and protein deficiencies can occur.

If the diet predominantly contains foods of lower protein quality this may increase the total amount of protein needed (generally refers to vegetarian based diets. My comment: I have seen very few athletes who seem to do well on a vegetarian type diet. My suggestion is consume adequate amounts of lean meats with low fat dairy products.

Calorie intake plays a key role in determining protein requirements. My comment: higher caloric intake generally means you need to consume less protein. Early studies showed that athletes gain strength and maintain muscle mass even during periods of low protein intake, assuming caloric intake is sufficient.

Many athletes attempt to drop bodyweight while maintaining or minimizing loss of lean mass. Numerous studies support the role for higher protein diets under these conditions. My comment: studies indicate huge losses in bodyweight while maintaining bodily proteins if protein intake is sufficient. Suggestions vary for what is sufficient as this depends on a multitude of factors. I have seen cases where athletes actually gain skeletal muscle while losing body fat. Keep in mind under most circumstances the simultaneous gain of skeletal muscle and loss of body fat does not occur, but it seems to occur often in obese newbie trainees, and individuals who increase protein intake substantially above previous levels. In fact, I had a female figure competitor who recently dropped a significant amount of body fat while simultaneously increasing muscle tissue. I would think this was due to her drastic change in diet. Her previous diet was the typical American diet while her pre-comp diet was substantially higher in protein, moderate in carbs and fat, and relatively high in fiber. She reported feeling better, getting stronger, and she definitely looked better although her calorie intake was about 20% below her calculated maintenance level. The last bodybuilding show I competed in I experienced similar results in the first 4-5 weeks of my pre-comp diet.

On a whole body-level, studies suggest that although vegetarian diets may be sufficient for positive nitrogen balance, reliance on animal proteins results in superior balance. Although a study by Jannelle stated the clear superiority of animal proteins might not be so clear.

A problem with whole-body studies is they do not give a clear picture of the importance of protein intake to other tissues, particularly muscle. In a series of experiments using stable isotopes is has been determined in general, use of amino acids from animal proteins (milk) is greater than plant proteins (wheat). This suggests that amino acids from different sources may be utilized by different tissues. Amino acids ingested as milk proteins are taken up in greater amounts by peripheral (muscle) rather the splanchnic tissues (visceral or relating to visceral).

Phillips and colleagues reported that uptake of amino acids from milk proteins into muscle is greater than from soy protein after resistance exercise. One a muscle level after resistance exercise, the differences in amino acid uptake between casein and whey proteins are unclear. My comment: there is research that supports the superiority of both proteins in regards to net muscle protein balance. I would suggest consumption of both proteins. Both proteins have their benefits and can be beneficial to athletes.

At rest, carbohydrate consumption with protein increases whole body amino acid retention. It has been shown that carbohydrate ingestion increases the use of amino acids after resistance exercise, an effect likely contributed to the insulin response. My comment: if insufficient amino acids are present insulin will not promote MPS.

In a previous study the anabolic response to a solution of EAA and carbohydrates immediately before exercise was approximately three times greater than when the solution was ingested after exercise. In a more recent study using and identical protocol, the response to an ingestion of whey proteins immediately before exercise was similar to that after exercise. My comment: this study conducted by Tipton showed that the response was different for an intact protein than an EAA and carbohydrate solution. Tipton suggested the results might have been different if the whey had been consumed further in advance before the workout. Consuming the whey one hour before workout would have allowed a peak in blood amino acid levels as the workout began.