Proteins provide the body critical amino acids that serve as
building blocks for the formation of new muscle. But not all
dietary proteins are equal. The major proteins in milk are
casein and whey. These two milk proteins are both excellent
sources of all the essential amino acids, but they differ in one
important aspect—whey is a fast-digesting protein and casein is
a slow-digesting protein.Whey stimulates protein synthesis Fast-
digesting whey means it is emptied from the stomach quickly,
resulting in a rapid and large increase in plasma amino acids.
This translates into a quick but transient increase in protein
synthesis, while protein breakdown is not affected. Whey also
has higher levels of leucine, a potent amino acid that
stimulates protein synthesis. Whey protein is superior at
augmenting protein synthesis rapidly, but this positive effect
is short-lived. Consuming repeated doses of whey allows for
sustained high levels of blood amino acids and repeated bursts
of protein synthesis that provide superior