T3 in the body is responsible for regulating the uptake of various nutrients into cells and into the mitochondria of those cells in order to effectively become utilized for the production and consumption of energy. The mitochondria of every single cell in the body utilizes carbohydrates, fat, and even protein for the production of an energy source known as ATP (Adenosine Triphosphate). Through the intake of more T3, this production of ATP will increase, leading to an increased rate of energy consumption in the form of fats, carbohydrates, and protein. Hence, this is why the consumption of too much T3 without the use of anabolic steroids can result in muscle loss.

T3 is also commonly combined with other fat loss agents in order to increase its overall effect, as it does work synergistically with other fat loss agents.