The body cannot synthesize the essential amino acids (EAA), which are the building blocks of proteins. We must therefore obtain them from the diet or from supplementation. They are important for various physiological functions such as growth, development and maintenance of the body, and are necessary for the maintenance of muscles.

EAA supplementation for muscle mass gain is very popular with athletes, and sufficient intake of essential amino acids and high quality protein is also important to address muscle catabolism in dieting and definition phases.

The diet must provide these nine essential amino acids, and the most common sources are meat, poultry and eggs, or supplementation. EAAs are suitable for people who struggle to get enough protein every day, such as people who don't have time to eat, people who travel, skinny people who have trouble gaining weight, vegans, people in the lean phase who want to keep as much muscle mass as possible, people who can't tolerate protein powders, and people with a smaller appetite.