“Whey Protein but Not Soy Protein Supplementation Alters Body Weight and Composition in Free-Living Overweight and Obese Adults”
That’s the title of a study from the Journal of Nutrition, August 2011 edition. Here’s the basic set-up. Three groups, one drinks whey protein, one drinks soy protein, one drinks a carbohydrate solution – all equal in calories – in addition to eating regularly. This happened for 23 weeks.
Now, the title would have you believe that the whey group (WP) altered their weight and body composition significantly and the other two groups didn’t. What really happened is that WP did lose about a kilogram of bodyfat, the soy group stayed about the same, and the carb group gained 1.5 kilograms of bodyfat. So, the difference between the WP group and the carb group is significant, but only because the people who added and extra 30 grams of carbs to their diet in the form of maltodextrin gained weight as fat.
So, the real take-away message is don’t add unnecessary carbohydrates to your diet, especially in liquid form.
Baer DJ,* Stote KS, Paul DR, Harris GK, Rumpler WV, Clevidence BA. Whey Protein but Not Soy Protein Supplementation Alters Body Weight and Composition in Free-Living Overweight and Obese Adults. J Nutr. 2011