Casein makes up 80% of the protein found in milk. It’s found in higher concentrations in cottage cheese and Greek yogurt. Casein’s unique effects arise from how it’s absorbed and digested. Unlike whey, casein is absorbed slowly, increasing but not spiking blood amino-acid levels. Casein’s anti-catabolic properties result from these sustained increases in blood amino-acid levels, which is ideal for optimizing the balance between muscle breakdown and muscle building. Research shows that casein eaten late at night can improve muscle building and recovery from exercise while you sleep.