Branched-chain amino acids, or BCAAs, are a group of three essential amino acids: leucine, isoleucine and valine. These BCAAs, particularly leucine, have shown to be the key nutrient for turning on protein synthesis in muscle.
As you exercise, amino acids, particularly the branched chains, gradually deplete. If this goes on long enough, muscle protein breakdown occurs and you go from muscle building to tearing it down.
Since branched chain aminos are already broken down into individual amino acids, they are utilized immediately. As soon as they hit the small intestine they're immediately absorbed into the blood stream and on their way to where you need them – muscle.
When you're supplementing BCAAs, bear in mind that the 2:1:1 Ratio of leucine to valine to isoleucine is the only ratio that has scientifically backed studies to show that BCAAs positively effects protein synthesis after training.
However, more recent studies have demonstrated that a heavier leucine load is even more effective overall in helping you gain lean muscle mass. That's why my Proven EAA's give you a super heavy leucine load in a 4:1:1 ratio.
According to more recent research, the daily requirements for branched chains may actually be as high as 12 grams a day for a man. While the average person can probably get all he needs from food, your daily requirements are going to be higher if you’re an athlete doing heavy resistance training. Most of the studies that showed a benefit in trained individuals who used supplement doses ranging from 10–20 grams of BCAAs per day, in a leucine heavy 2:1:1 ratio, taken before and during resistance training.