A new study came out this past week that did a long-term comparison of supplemental nutrient shakes of different macro-nutrient composition (macronutrients are carbs, protein, fat, and water). To sum up the framework and methods of the study...
1) There were three groups
2) One group was given a whey protein shake, one a soy protein shake, and one a carbohydrate shake. Each shake was the same number of calories: 200.
3) All of the participants were required to keep a food journal, and activity journal.
4) The study lasted 6 months.
5) All in all, all three groups ate about the same number of calories each day (2200), and had the same activity level (almost none).
When the results were analyzed, what the researchers found was the the whey protein group had lost 2 pounds, the soy protein group stayed the same, and the carbohydrate group gained 2 pounds. The whey protein group also trimmed an inch off their waistlines.
Now, 2 pounds and one inch are not exactly a lot of weight-loss over 6 months, and could be potential insignificant in the grand scheme of things, BUT there are other things to take from this article. First, 2200 calories for a sedentary individual will almost always result in gradual weight GAIN. The fact that the whey protein group lost weight when the caloric intake shows they should have gained weight is very noteworthy. Second, most whey proteins of good quality have BCAA (branch chain amino acids) which have been proven to increase lean muscle mass, even in people who don't work out.
In a study completed last year, BCAA's were given to a group of 70-something sedentary men. All the experiment did was give these guys BCAA and nothing else. They didn't change their diets, nor did they increase activity. The result? Every person in the group increased lean muscle mass.
I have yet to see any studies that produce the same results by ingesting soy protein. So, big picture here, although soy protein gets the vegetarian/organic/I only shop at Whole Foods seal of approval, it is worth noting that whey protein has multiple (potentially significant) advantages over soy.
Yes, yes, I know soy has more anti-oxidants, but if you are eating a well-rounded colorful-vegetables-included diet, then more than likely you are achieving your requirement for anti-oxidants. You know you get anti-oxidants from red wine, too right...?
Oh yeah, one more thing, men who over-consume soy protein...their estrogen levels go up. So, ladies if you want your husband/boyfriend/office hook-up to have more muscles, have them consume whey. If you want the overly-sensitive, "I've memorized Dirty Dancing" type guy, load him up on soy...and get a box of tissues.