Written by Anssi H. Manninen, MHS
03 October 2006

Whey Protein Hydrolysate Increases Muscle Mass & Strength While Decreasing Body Fat


A recent study, published in the International Journal of Sports Nutrition and Exercise Metabolism, examined the effects of supplementation with different proteins, namely hydrolyzed whey protein and casein (the main component of milk protein), on muscle strength and body composition during a 10-week, supervised resistance training program.1 Importantly, this study was conducted on experienced male bodybuilders. In a double-blind protocol, these guys supplemented their normal diets with either whey hydrolysate or casein (1.5 grams per kilogram of body mass per day). What happened? Well, this well-controlled study indicated that:

  • 1. The whey hydrolysate group achieved a significantly greater gain in lean body mass than the casein group (5.0 versus 0.8 kilograms). Also, the whey hydrolysate group lost significant body fat while the casein group gained body fat (-1.5 versus 0.2 kilograms).
  • 2. The whey hydrolysate group also achieved significantly greater improvements in muscle strength (measured by barbell bench press, squat and cable pulldown) compared to the casein group in each assessment of strength. Furthermore, when the strength changes were expressed relative to bodyweight, the whey group still achieved significantly greater improvements in strength compared to the casein group.

In conclusion, it now appears that high-quality whey protein hydrolysate is the ultimate source of protein for serious, strength-power athletes.



1. Cribb PJ et al. Int J Sports Nutr Exerc Metab, 2006;16(5).