HMB stands for beta-hydroxy beta-methylbutyrate. It is a metabolite of leucine, one of the body's essential amino acids, with small amounts found naturally in catfish, grapefruit and alfalfa.

It has become very popular amongst athletes in recent years mainly due to the role it plays in the synthesis of muscle tissue. HMB has been subjected to many studies that have reached some interesting conclusions. One study showed that supplementation with 3 grams of HMB per day increased participants' strength by a factor of three compared with placebo takers. Supplementing with the same amount also saw a reduction in bad cholesterol compared with the placebo group.

Clearly there is significant scientific backing for claims that HMB can speed up muscle growth, strength, endurance and fat loss. There are no known side effects when taken properly in amounts ranging from 3-5 grams each day. It should be taken before training or at bed time for best results.