http://www.bodybuilding.com/fun/berardi1.htm
SUMMARY:
With all the media hype out there, the key to staying lean and mean is still diet, specifically, good food choices.
A calorie is not a calorie because the macronutrient content of each meal affects the body's response to the feeding. That basically means you could change your body composition by eating the same amount of calories each day, but making different food choices. Meal timing also plays an important role.
A high protein diet may be better than a moderate protein diet for fat loss.
A protein is not a protein because different kinds of proteins affect the body in different ways. Milk protein isolate (80% casein, 20% whey) may be better than whey alone if your goal is fat loss. Whey looks like it's better for antioxidant protection, however.
A supplement containing whey + casein may be your best bet for body composition improvements.
Meat eaters can lose fat faster and gain more muscle than vegetarians, even if the vegetarians eat the same amount of calories and get the same amount of protein.
Eating fish may improve your carbohydrate sensitivity and ultimately your body composition.
Soy still sucks as a primary protein source.