Bodybuilders and athletes have used Branched-chain amino acids for many years for their clinically-proven ability to increase protein synthesis and thus increase muscle growth and decrease recovery time. BCAA's are also used for burn victims and in other medical applications for the same purpose, as they greatly improve healing and recovery from such injuries. Few supplements in the sports performance arena have the amount of clinical evidence supporting their effectiveness; and for this reason, BCAA's are a widely used and trusted staple to many fitness and performance oriented diets. Recent evidence has emerged that BCAA's have an even greater benefit in calorie deficient diets and for purposes of fat loss. The effects are three-pronged as BCAA's decrease appetite while increasing metabolism, decrease the breakdown of muscle protein on a restricted diet and also greatly reduce perceived exertion in training, allowing you to train longer and harder while energy deficient.
A major benefit of supplementing with BCAA's on a restricted diet is the direct effect they have on brain signaling that both decreases appetite and increases metabolism. A December 2012 study released by the Division of Endocrinology and Metabolism at the University of Texas Medical Branch outlined that Branched-chain amino acids, particularly leucine, had a profound effect on the anabolic actions of the mTOR pathway to muscles. In addition to this, BCAA's have an effect on both insulin sensitivity and interact with the brain chemical serotonin to reduce cravings and hunger. Anabolic signaling tends to decline in lower calorie diets as well as with aging and BCAA's reverse this decline to a degree. Further research from the Massachusetts Institute of Technology has demonstrated that the addition of B vitamins further enhances anabolic signaling and even helps direct amino acids to muscles. Basically, this means BCAA's make you less hungry, burn more calories, and direct the energy you do use to muscle protein and away from fat, even more so in the presence of B vitamins.
The ability of BCAA's to inhibit the breakdown of muscle protein is two-fold. As we diet and body fat drops and fewer calories are available through food or stored body fat, our body turns to our muscle as the primary source of energy. The body breaks down muscle tissue into its amino acids components as use for energy. Supplementation with BCAA's both provides fuel for the body to use directly instead of catabolizing hard-earned muscle, but also, as mentioned before, effect signaling to the muscles that inhibits their breakdown for energy needs.
The other way BCAA's contribute to success in fat loss is their unique ability to decrease perceived exertion in a workout. As we restrict our diets and get lower and lower in body fat stores, workouts become increasingly difficult as we simply don't have the energy to push through and tire quickly. A November 2012 study by the University of Sao Paulo in Brazil took two groups of rats, one with and one without BCAA supplementation pre-workout and ran the rats through a swimming test until complete exhaustion. What they found was the BCAA group increased their time until exhaustion by 37%. That is the equivalent of going two hours in the gym as opposed to 1 1/2 hours. The reason is that BCAA's both provide energy to the body and also interfere with fatigue causing ammonia and lactic acid in muscles. A study out of Truman State University in Missouri showed that Alpha-Ketoisocaproate, or Alpha-KIC, which is very similar to the BCAA leucine can be used alongside BCAA’s and enhance their effects to further improve performance.
Overall, BCAA's should be included regularly in any athlete-focused reduced calorie diet to aid in fat loss. While they work wonders, they are also dose dependent. Too much BCAA's has been shown to decrease their effectiveness. Allmax Nutrition recommends 8,180 mg's in their Aminocore. Aminocore uses a clinically proven and unique ratio of BCAA's and is also fortified with anabolic supporting B Vitamins as well as fatigue fighting Alpha K.I.C. Branched-chain amino acids from products like Aminocore combined with a quality but restricted diet and exercise will result in much better results than diet and exercise alone.