In healthy young adults, consumption of 20 grams of high-quality protein or 10 grams of essential amino acids per meal maximally stimulates muscle protein synthesis, with no additional increase observed at higher doses.

When you eat 20 grams of high-quality protein, the amino acid leucine enters your muscles and turns on a molecular switch called mTORC1, which tells your cells to start building new muscle proteins. This switch stays on just long enough to build as much muscle as it can. Once enough proteins are made, the cell's internal factory gets overwhelmed and triggers a safety brake that stops further protein production, even if more amino acids are still present.