Calorie-Burning BCAA

Recently, researchers found that adding a small amount (~0.6% of their diet by weight) of supplemental L-leucine to the normal diet of rats promoted weight loss.

When the animals fed the control diet (i.e., the normal diet with no added L-leucine) were compared with the rats fed the experimental diet (the normal diet plus L-leucine), significant differences in the total amount of food consumed and the amount of body fat between the two groups were observed.

Rats that ate the L-leucine-augmented meals lost nearly 23% more body fat than the group that was fed the control diet. Some of this is attributable to the fact that the rats that were given the experimental diet ate about 24% less food than their counterparts who did not get the L-leucine.

While the authors of this study note that supplementation with only one type of branched chain amino acid (BCAA) might impair the availability of L-isoleucine and L-valine, the benefits observed in this study out-weighed the potential side-effects. Moreover, there were no differences in the mass of the skeletal muscle or vital organs of the experimental rats despite the significant loss of body fat.

The Bigger Picture: Commonly taken to preserve lean muscle mass and to help with post-workout recovery, the BCAAs particularly L-leucine may be beneficial for weight loss too. BCAAs have been shown to elevate the rate of protein synthesis and the oxidation of energy from stored body fat appears to provide at least some of the additional energy required for this process. While this study involved animals, rather than human subjects, the scientists believe that the positive results are relevant for human applications as well. L-leucine appears to be the most important of the three BCAAs, but a supplement containing L-leucine, L-isoleucine, and L-valine may be better.
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