Essential amino acidsEAAs

Essential amino acids (EAAs) are the nine amino acids your body cannot synthesise and must obtain from protein in the diet. All nine are needed together to build new body proteins, including muscle.

It matters because muscle growth requires the full set of EAAs, not just one or two — which is why a complete protein (containing all nine in good amounts) is more effective than fragments like BCAAs alone, and why protein source quality counts.

In practice, animal proteins and well-combined plant proteins supply all the EAAs; eating enough complete protein across the day is what matters, rather than supplementing isolated amino acids.