Two new studies shed light on another exciting benefit of whey—it accelerates glucose uptake and glycogen synthesis after exercise. Glycogen is the storage form of carbohydrate in the body and plays a role in preventing fatigue and enhancing performance.
In the first set of experiments, researchers studied animals that performed exhaustive exercise to deplete muscle glycogen. Control animals received carbohydrates only after exercise, whereas four other groups received carbohydrates plus different forms of protein including whey, whey hydrolysates, branched-chain amino acids (BCAAs) and casein hydrolysates. Muscle glycogen levels measured two hours after exercise revealed the groups fed whey and whey hydrolysate had dramatic increases—nearly two-fold greater than the carbohydrate-only and casein hydrolysate groups.
To better understand why whey outperformed the other proteins, the researchers studied specific BCAA dipeptides—two amino acids linked together—from beta-lactoglobulin, one of the main proteins in whey. They showed several dipeptides that included leucine increased glucose uptake into muscle and glycogen storage.
Whey protein, specifically certain BCAA dipeptides present in whey positively impact glucose metabolism by increasing glucose uptake and accelerating glycogen synthesis after exercise. These studies also indicate that whey may be useful for both athletes and those with insulin resistance.