Whey is the liquid that separates from the curds of milk during cheese-making, and it is a byproduct that is a complete protein source containing all essential amino acids.

Casein is the primary protein found in milk (about 80%). It’s what gives milk its white color and is responsible for forming the curds in cheese. Unlike whey, casein digests slowly, releasing amino acids steadily over several hours. This makes it ideal for muscle maintenance, overnight recovery, and satiety, rather than rapid post-workout repair like whey.

Proteins are made up of 20 different amino acids. Nine of these amino acids are essential, meaning the body cannot produce them and must be obtained from the diet.