If you're putting on weight, a diet containing extra BCAAs may help you build up less fat mass. Japanese researchers discovered, when doing experiments with mice, that the liver and muscles play a key role in the fat-mass reducing effect of BCAAs.
Athletes use BCAAs mainly as an anticatabolic supplement. They usually take somewhere between 5 and 25 g before training and notice that this helps them to recover faster.
BCAAs were originally marketed in Japan as clinical nutritional aids. They strengthen liver functioning and also have a positive effect on the insulin and glucose metabolism. Liver disease and diabetes are also possible effects of overweight. Which is why the Japanese wondered whether BCAAs could help to limit the negative health effects of the current obesity epidemic.
The researchers gave their mice feed consisting of 45 or 65 percent fat for six weeks. The mice put on weight fast on these diets. After four weeks the Japanese added BCAAs to the drinking water of half of the lab animals. One ml drinking water contained 20 mg BCAAs.
The BCAA supplementation had no effect on weight gain in the mice that were given feed consisting of 65 percent fat, but it did have an effect on the 45 percent fat group.
The researchers are not able to explain this. The BCAAs didn't stop the mice from getting fatter, but they did reduce the speed with which the mice built up fat mass, as the figure below shows. What's more, the BCAA animals had fifty percent less white fat tissue [WAT] than the mice in the control group.
The researchers actually found that the supplementation had the greatest effects in the muscle and liver cells rather than in the fat cells. They found fifty percent less fat [triglycerides] in these cells in the BCAA mice, and much greater activity in the molecules that are involved in fat burning, such as the fat sensor PPAR-alpha, the enzyme COT-1 and the uncoupling proteins 2 and 3. CPT-1 helps the cells to burn fatty acids; uncoupling proteins boost the heat production in cells.
Many athletes who use BCAAs say that they lose noticeable amounts of fat. The Japanese research shows that these athletes may be right.
Endocr J. 2011; 58(3): 161-70.