WHEY PROTEIN ISOLATE BUILDS MUSCLE MASS: AS-IT-IS Nutrition Whey Protein Isolate is a rich source of protein which aids in the growth and maintenance of muscle mass. WHEY PROTEIN ISOLATE IS HIGH IN BCAAs: AS-IT-IS Nutrition high-quality Whey Protein isolate is rich in branched-chain amino acids leucine, isoleucine and valine, This makes Whey Protein Isolate give that ideal push to bodybuilders.