Isoleucine's roles include working with leucine and valine to repair muscle, control blood sugar, and provide energy to body tissues. It also boosts the production of growth hormones and helps burn visceral fat, which, because it's inside the body, can't be effectively affected by diet and exercise alone.
Good sources of isoleucine include brown rice, beans, meat, nuts, soy meal, and whole grains. Since it is an essential amino acid, this means the body cannot produce it on its own, only through the diet. People engaged in high levels of physical activity and low protein diets should consider taking a white acid supplement.