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HMB – HydroxymethylButyrate – Review of Performance Enhancing Effects

HMB – HydroxymethylButyrate – Review of Performance Enhancing Effects

Beta-hydroxy-beta-methylbutyrate (HMB) is a leucine-derived metabolite.  Both the amino acid, leucine, and its metabolite a-ketoisocaproate (KIC) have been studied for years for their potent anti-catabolic effects.

Leucine itself has been the focus of many recent studies as well.  As an essential amino acid, leucine cannot be synthesized by your body, so it has to come from dietary sources.

Consequently, beta-hydroxy-beta-methylbutyrate production also depends on your intake of leucine.  However, there are also numerous dietary supplement companies that make various products containing HMB.

A recent review article focusing on ß-hydroxy-ß-methylbutyrate was published in the journal, Amino Acids, (Zanchi et al, 2010).

From the study, here are some of the key points:

Beta-Hydroxy Beta-Methylbutyrate Study:

  • A person weighing 70 kg would need to consume 60 g of l-leucine to produce 3g of HMB.  To consume  60 g of l-leucine per day from dietary sources would be possible,  but not typically very feasible given the % of leucine in typical protein sources.  In other words, to achieve the typical dose of 3 g/day of HMB used in studies, you would likely need to take an HMB supplement.
  • Most studies on ß-hydroxy-ß-methylbutyrate are based on dosages of 3.0 or 6.0 g HMB/day.  The 3.0 g/day dose has been shown to be more effective than 1.5 g/day and equivalent to the 6.0 g/day dose.
  • A meta-analysis by Nissen and Sharp (2003) concluded that the effects of HMB on strength and lean mass are statistically significant (when combined with resistance training).  This study has faced some criticism, however, and there is some heterogeneity in the literature.
  • Duration of supplementation for these studies typically ranged from 10 days to 12 weeks with the longer duration studies generally having more favorable results.
  • Previous research suggests an additive benefit of supplementing HMB with creatine with a greater gain in strength and mass for the group that supplements with both than either alone.

From the study authors, they also note some possible therapeutic uses of this supplement:

“Finally, the therapeutic use of this supplement is quite promising. Additional clinically controlled studies, with important primary endpoints, must be conducted in patients with AIDS, trauma, cancer, malnutrition, and inflammation, among other frameworks of severe catabolism.”

* HMB seems to be safe when taken in standard doses for short periods of time (Nissen et al, 2000). Full safety studies have not yet been performed. Future studies are necessary to better understand the mechanism of action, safety, effectiveness, and optimal dosage of HMB.

A previous study had shown beta-hydroxy-beta-methylbutyrate to have positive effects on aerobic performance.


  1. Zanchi NE, Gerlinger-Romero F, Guimarães-Ferreira L, de Siqueira Filho MA, Felitti V, Lira FS, Seelaender M, Lancha AH Jr.  HMB supplementation: clinical and athletic performance-related effects and mechanisms of action. Amino Acids. 2010 Jul 6.
  2. Nissen SL, Sharp RL (2003) Effect of dietary supplements on lean mass and strength gains with resistance exercise: a metaanalysis. J Appl Physiol 94(2):651–659.
  3. Nissen S, Sharp RL, Panton L, Vukovich M, Trappe S, Fuller JC Jr:  β-Hydroxy-β-Methylbutyrate (HMB) Supplementation in Humans Is Safe and May Decrease Cardiovascular Risk Factors.


  • Doug

    Jarret, I am a big fan of leucine and have found that it is extremely helpful for maintaining muscle mass while attempting to burn off body-fat. In your opinion, do you see HMB as being more of a "performance" supplement, or would it be helpful as an anti-catabolic to help retain muscle while dieting?

    • Jarret Morrow, M.D.

      In my opinion, based on the current research, I think it could be a good choice for both. Some of the less recent studies had some promising results when combined with creatine for improving strength gains and lean muscle mass. Though the mechanism of action isn't completely understood yet, it's been shown to have anti-catabolic effects in a few different models as well.

  • Joe Cannon MS CSCS

    While I wouldn't totally rule out an effect of a large amount of HMB, the research I have seen appears to show best effects in untrained people. The last time I checked (over a year ago), the research direction of Metabolic Technologies (the makers of HMB) was more toward sick people (cancer HIV etc) with less emphasis on exercise. Joe

  • Jarret Morrow, M.D.

    Joe, Thanks for stopping by and sharing your thoughts. As the authors of this recent study noted, there is some heterogeneity in the results of HMB studies. Some of this heterogeneity can probably be attributed to variations in dosage, length of studies, training stimulus, and outcome measures. You're absolutely correct that some of the earlier research suggest that previously untrained individuals have demonstrated greater effects from supplementing with HMB than previously trained athletes. The authors of this recent study attribute this to previously trained individuals exhibiting greater degrees of muscle breakdown in response to training stimulus than previously trained athletes. They also suggested that future studies should use training protocols that are sufficiently intense for previously trained athletes to determine HMB's effectiveness in this group. I'm not personally aware of the research direction of Metabolic Technologies, but it definitely makes sense that they would pursue research on therapeutic uses for patients (with medical conditions involving catabolism).

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