Also known as: Beta Hydroxy-Beta-Methylbutyrate
Where is it found?
Small amounts of HMB are present in many foods of animal and plant origin, especially alfalfa and catfish. The amino acid leucine is metabolized into a compound
called alpha-ketoisocaproate (KIC), which is then turned into HMB by the body. Dietary
supplements of HMB are also available.
Why do dieters use it?*
Some dieters say that HMB
- promotes the loss body fat.
- helps build muscle.
- helps increase strength.
- speeds recovery between workouts.
- reduces post-workout soreness.
What do the advocates say?*
HMB may assist in accelerating the loss of body fat.
Exercise-induced muscle protein breakdown appears to decrease with HMB supplementation.
This, in turn, should speed up recovery from exercise-induced muscle damage.
Enhanced strength and increased muscle mass have been documented in people supplementing
with HMB. However, to date, a very limited number of studies have been done. Longitudinal
studies to indicate possible long-term use effects of HMB have not been completed.
How much is usually taken by dieters?
Biochemical and animal research shows HMB has a role in protein synthesis and might improve
muscle growth and overall body composition as a supplement. However, double-blind human
research suggests that HMB may only be effective when combined with an exercise program in
people who are not already highly trained athletes. Double-blind trials found no effect of 3
to 6 grams per day HMB on body weight, body fat, or overall body composition in
weight-training football players or other trained athletes.1 2
3 4 5 However, one double-blind study found that 3 grams per day
HMB increased the amount of body fat lost by 70-year old adults who were participating in a
strength-training program for the first time.6 A double-blind study of young men
with no strength-training experience reported greater improvements in muscle mass (but not in
percentage body fat) when HMB was used in the amount of 17 mg per pound of body
weight.7 However, another group of men in the same study given twice as much HMB
did not experience any changes in body composition.
Are there any side effects or interactions?
No safety issues have been reported in the limited number of studies currently
available.
At the time of writing, there were no well-known drug interactions
with HMB.
*Dieters and weight-management advocates may claim benefits for HMB
based on their personal or professional experience. These are individual opinions and
testimonials that may or may not be supported by controlled clinical studies or published
scientific articles on HMB. For more complete and detailed information, including references
and safety information, see HMB as a nutritional
supplement.
References:1. Ransone J, Neighbors K, Lefavi R, Chromiak J. The Effect of
beta-hydroxy beta-methylbutyrate on muscular strength and body composition in collegiate
football players. J Strength Cond Res 2003;17:34–9.
2. Kreider R, Ferreira M, Wilson M, Almada AL. Effects of calcium
beta-HMB supplementation with or without creatine during training on body composition
alterations. FASEB J 1997;11:A374 [abstract].
3. Slater G, Jenkins D, Logan P, et al. Beta-hydroxy-beta-methylbutyrate
(HMB) supplementation does not affect changes in strength or body composition during
resistance training in trained men. Int J Sport Nutr Exerc Metab 2001;11:384–96
[review].
4. Kreider RB, Ferreira M, Wilson M, et al. Effects of calcium
beta-hydroxy-beta-methylbutyrate (HMB) supplementation during resistance-training on markers
of catabolism, body composition and strength. Int J Sports Med
1999;20:503–9.
5. Slater GJ, Jenkins D. Beta-hydroxy-beta-methylbutyrate (HMB)
supplementation and the promotion of muscle growth and strength. Sports Med
2000;30:105–16.
6. Vukovich MD, Stubbs NB, Bohlken RM. Body composition in 70-year-old
adults responds to dietary beta-hydroxy-beta-methylbutyrate similarly to that of young adults.
J Nutr 2001;131:2049–52.
7. Gallagher PM, Carrithers JA, Godard MP, et al.
Beta-hydroxy-beta-methylbutyrate ingestion, Part I: effects on strength and fat free mass.
Med Sci Sports Exerc 2000;32:2109–15.