The BCAAs are made up out of three essential amino-acids: leucine, isoleucine and valine. They are essential because the body is unable to make them out of other amino-acids, meaning they have to be ingested through food or supplements.
They enhance muscle protein synthesis and will prevent the muscle breakdown during intense workouts. Their branched components simply the job of converting each amino acid into energy.
BCAAs increase fat burning & glucose tolerance to keep you lean. They support the hormone balance so people will be able to respond to extreme training loads.