If you’re already working on building muscle and eating enough to complement your gym routine, you’re probably at least passingly familiar with how important protein is in your diet. In a nutshell: protein is one of the three macronutrients. Proteins have several important roles including helping repair tissue, forming important enzymes and hormones, as well as acting as “building blocks” for many different tissues and organs in your body, including your muscle.
Proteins are complex molecules that are made up of different combinations of individual amino acids. There are a total of 20 amino acids which make up thousands of different proteins. Your body can endogenously make 11 of these amino acids on its own. However, it can’t make the remaining 9 amino acids, which means that you need to get them from the foods that you eat instead. These 9 amino acids are therefore referred to as “essential amino acids” (EAA for short). Three of those essential amino acids are the BCAAs valine, leucine, and isoleucine.
If a food source is a “complete” protein source, this means that they contain all nine essential amino acids (whey protein is a good source of this). Meanwhile, an incomplete protein source will only have some of the EAAs.
So to sum this up: Amino acids, including the three BCAAs, are the “building blocks” of protein molecules, and those whole protein molecules then make up the structure of your muscle tissue.