Hydroxy-methylbutyrate
(beta-hydroxy-beta-methylbutyrate or HMB)

Hydroxy-methylbutyrate is a metabolite of the essential amino acid leucine. It inhibits protein breakdown. Bodybuilders and other highly trained athletes use HMB as a supplement to increase muscle mass.

Two studies show that hydroxy-methylbutyrate decreases fat mass and increases lean body mass. This is encouraging, but more studies need to be performed.

Although the studies mentioned above did not report any side effects, keep in mind that some side effects only show up after serval large studies are done.
 

It is important you discuss any weight loss or exercise plan with your doctor. Only you and your physician can decide what is best for you. Some people have certain conditions that prevent them from doing all exercises, and goal body weights may be different for different people. You need to discuss all these things with your physician before starting any weight loss or exercise program.