is considered to be a superior protein source for a number of reasons. One reason closely related to gaining muscle is the rich content of essential amino acids found in whey, especially the branched-chain amino 
acids. But recently, the price of whey supplements has escalated dramatically. As a result, many companies are turning to diluting pure whey protein products with other protein sources that are considered inferior to whey, but also far less expensive. One example of this is soy. While soy protein 
has engendered a nefarious reputation among bodybuilders because of its content of estrogenlike compounds called isoflavones, many studies have shown that the negative effects of soy are not that bad, as long as small amounts of soy are ingested. But how does soy compare to whey in terms of body composition?This is the precise focus of a forthcoming study. The study featured a randomized, double-blind design, considered the gold standard among research studies. The goal of the study involved comparing the effects of whey, soy, and carbohydrate alone on the bodyweight and body composition of free-living overweight and obese, but otherwise healthy adults. As such, the study consisted of 90 subjects who were randomly assigned to one of three treatment groups:
1) Whey protein
2) Soy protein
3) Carbohydrate containing the same number of total calories as the protein groups
Both protein groups ingested 56 grams of protein a day, consumed as a drink twice daily. Those in the carb group also consumed a drink twice daily. Other than the drinks, the subjects continued to eat their normal meals, and weren't provided with any dietary advice. The study lasted for 23 weeks, and bodyweight and body comp tests were done monthly. After 23 weeks, bodyweight and body comp didn't differ between the groups consuming whey or soy, or between soy and carbs. But the bodyweight and the fat mass was 1.8 kilograms and 2.3 kilograms lower in the whey group compared to the carb group. Lean mass didn't differ between any of the groups, which isn't unexpected since there wasn't any exercise component involved. Despite this, however, waist circumference was smaller in the whey group compared to the other groups. Most interesting was that the whey group alone showed lower resting levels of ghrelin,
a protein associated with increased hunger between meals. As a result, this study suggests that whey contains elements that may make it easier to lose bodyfat and stay on a diet compared to other sources of protein and carbs.Baer DJ, et al. Whey protein but not soy protein supplementation alters body weight and composition in free-living overweight and obese adults.J Nutr 2011: in press.
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