Leucine is an Essential Amino Acid (EAA) that is part of only three EAAs that form the subgroup called Branched-chain Amino Acids (BCAAs).
BCAAs are different from the other EAAs because they are metabolized in your muscles and not your liver, like the other EAAs.
BCAAs, especially Leucine, increase Muscle Protein Synthesis that may help you Build More Muscle and Recover Better from your workouts. 
Muscle Protein Synthesis, or the creation of new muscles, requires an adequate amount Amino Acids to form the base that is used to form new muscle.
BCAAs are effective because of their role in activating mammalian target of rapamycin complex or mTOR. Leucine has been shown to play the most significant role in activating mTOR, but the other BCAAs also play a critical role, but to a much lesser extent.
The mTOR pathway plays a role in controlling if and when your body creates (anabolic) or destroys (catabolic) muscle tissue.
BCAAs are one of the most popular supplements and they've been around for quite a while. This is great, because that means that they've been researched and studies have shown that BCAAs, when taken in proper amounts and paired with resistance training, activate mTOR and turn on your body's Anabolic Muscle Building Centers. [3,4]
Think of mTOR as a highway with limited traffic capacity. The highway leads straight to more gains, but only so many cars can use the road at any given time. You want your best cars on the road at all times, don't you?
We recommend supplementing with a High Quality, Leucine Heavy BCAA Supplement to Maximize Results by providing all 3 BCAAs, which are necessary, but with a strong preference to Leucine, The Star BCAA!