One Beast Test includes casein.. Whey protein is absorbed into the blood stream relatively fast but also gets burned up just as fast and so much of the whey that one consumes after a workout will not actually be used in protein synthesis. On the other hand, casein takes longer to get absorbed but also stays in the body much longer. One Beast Test This duality of having both quick absorption and slow release proteins improves the muscle building process since some form of protein will always be available-the whey during the first few hours and casein over the next several hours. The reasoning is sound but whether this is what actually happens in practice is less clear. The three different studies I have seen all seem inconclusive.

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