Well, the main idea that is 'overlooked' in protein intake is if enough protein is taken in, you will at least more than cover your protein 'useage'. That is if and when your body needs amino acids for any normal function, with enough external protein intake, it will have a source to use rather than existing muscle tissue. So, excess protein intake does not necessarily lead to muscle growth, but pretty much insures 'keeping' existing muscle tissue.
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