Whey protein is a popular diet supplement among people of all ages. Baby formulas include it, as do nutrition shakes for the elderly. Weight-loss supplements contain whey powder as an appetite suppressor, yet young men buy whey protein powder by the gallon in hopes of building muscle mass.
Much of whey protein’s appeal is in its texture. Whey is the liquid left behind when milk is turned to cheese. The protein in whey is one of the two main proteins in milk, the other is a protein called casein. (When an acidic substance such as vinegar is mixed into milk, these two proteins will separate — the casein proteins glob together to form solids called curds, leaving the whey as a liquid.)
Whey protein may show up in your favorite baked goods or ice creamas a way to replace the consistency of fat without the actual fat.
Source: live science