Branched-Chain Amino Acids are key in making up 35% of the required amino acids that muscles need. The three acids that are BCAA's include leucine, isoleucine, and valine. These are it. There is no others that are considered in the type of supplement. Out of the nine essential amino aicds, these BCAA's are all included. This means that body can't produce this by itself. It has to be consumed and broken down. Something you may not have known is that this type of combination has been used to treat burn victims. The most widely known reason for taking this type of supplement with the three aminos is for bodybuilding. Most trainers believe that if you consume more of this combination of nutrients, your body can build more lean muscle tissue than if you were using normal protein supplements. Finally, there have been a few studies showing that your blood-sugar regulation can be improved with it. 

Personally, I know one of my friends that has started using a BCAA supplement and he seems to love it. In his own words he: "put 10 pounds of muscle onto his legs" after trying it for a few weeks. Obviously this was because he was focusing on legs, but the results probably hold true for the rest of the muscles. Since these are essential amino acids, you can be negatively affected and struggle to put on muscle mass if your diet contains little leucine, isoleucine, and valine.