Muscle Study Pits Whey Versus Soy

A study on humans consuming whey or soy protein has found greater lean muscle gains with whey.

Funded by the Dairy Research Institute, the study assigned 41 subjects to 20 g of whey protein concentrate or soy protein isolate daily for nine months. Subjects were assigned to resistance training three times daily and body composition was assessed every three months. After nine months, researchers observed a higher average gain in lean muscle mass with whey (3.3 kg) compared to soy (1.8 kg).

The U.S. Dairy Export Council proposes that whey’s naturally high levels of the amino acid leucine-an amino acid involved in the building of lean muscle-may have been a reason for the greater gains in lean muscle mass. Leucine is an essential amino acid for humans. It cannot be created by the body and must be obtained from food sources.

The study comparing whey protein and soy protein was presented at the American College of Sports Medicine (ACSM) Annual Meeting earlier this year.