Hydroxymethylbutyrate (HMB) is a chemical that is produced when the body breaks down leucine. Leucine is an amino acid, one of the building blocks of protein. People use HMB to make medicine.
HMB is used for increasing the benefits from weight training and exercise; and for treating diseases of the heart and blood vessels (cardiovascular disease), high cholesterol, and high blood pressure. In combination with the amino acids arginine and glutamine, HMB is also used for treating weight loss, weakness, and diarrhea in people with AIDS (AIDS-related wasting).
Increasing body weight and muscle in people with acquired immunodeficiency syndrome (AIDS). Taking HMB by mouth, along with the amino acids arginine and glutamine, seems to increase body weight and lean body mass in people with AIDS when used for 8 weeks. This combination may also improve the way the immune system works in these people.
Athletic performance. There is conflicting evidence about the usefulness of HMB for weight training. Some research suggests that taking HMB by mouth, alone or along with other supplements, might increase strength, improve body composition, and reduce muscle damage when used during resistance training or intense endurance exercises. However, other research suggests that HMB does not improve these outcomes. The reason for the conflicting results is not entirely clear. There is some evidence that HMB might be more effective in people who are just beginning to train than in well-trained athletes.
Disease-related weight loss (cachexia).
Some research shows that taking HMB by mouth, along with the amino acids arginine and glutamine, seems to increase body weight and lean body mass in people with cancer-related cachexia when used for 24 weeks. However, taking this combination does not seem to improve body weight or lean body mass in people with rheumatoid arthritis related-cachexia when taken for 12 weeks.
For treatment of weight loss, weakness, and diarrhea related to AIDS (AIDS-related wasting): 3 grams HMB in combination with 14 grams each of arginine and glutamine in two divided doses daily.