biochemie, supplementen

Latest meta-analysis on beta-hydroxy-beta-methylbutyrate (HMB)

In this research pick I’ll briefly go over a recent meta-analysis published in Journal of Science and Medicine in Sport named Effects of beta-hydroxy-beta-methylbutyrate supplementation on strength and body composition in trained and competitive athletes: A meta-analysis of randomized controlled trials [1]. I’m a bit amazed by the amount of research still done on HMB. It has been researched for well over 2 decades now and it has never proven to really do much for athletes outside of some really dodgy study results.

So what is beta-hydroxy-beta-methylbutyrate (HMB)?

HMB is a metabolite of the essential amino acid leucine. Leucine is considered a very important amino acid for building your muscle and some research suggests this might be (partly) due to its conversion to HMB. So that’s why they started testing this out.

On a decent proten intake of 150 g per day, it is estimated your body would produce about 0.75 g of HMB (~5% of leucine gets converted [2]). So the idea is that if you supplement a lot more than that (say, 3 gram), you’ll get the gains. Unfortunately, it seems to not do much, as I’ll discuss next.

Meta-analysis clearly states: NO EFFECT

So what did this meta-analysis do? They gathered studies with either trained or competitve athletes (for the definition of this, just check their paper) in which HMB got compared to a control/placebo group in either a randomized controlled or crossover manner. The studies had to include measurements of body mass, fat-free mass, fat mass, bench or leg press strength. And then they did some statistical fapping to assign appropriate weights to the studies and add them up. Because that’s what meta-analyses do: throw a bunch of studies together as if it was one single study, so you get more statistical power. Of course you need to weigh some study heavier than the other, so that’s what they did.

What did they find? Well, the conclusion is quite clear in this and states: “This meta-analysis found no effect of HMB supplementation on strength and body composition in trained and competitive athletes.”

Indeed, if you check out their forest plots, you’ll see that for bench press, body mass, leg press, fat-free mass and fat mass the ‘diamond’ clearly crosses the no effect line:

And don’t let the fat-free mass diamond fool you, that’s still a P-value of 0.31. Same for the fat mass diamond, that’s a P-value of 0.19. If there is an actual effect of HMB on these measurements, it’s really really small, making it very hard to detect at all.

Even after further analyzing results, they couldn’t find anything: “These results remained constant even analyzing by subgroups (HMB doses, duration of intervention, training level and diet co-intervention).”


So there’s this study by Jacob Wilson, which showed dramatic increase in strength and muscle mass after HMB supplementation [3]. This study actually wasn’t included in the meta-analysis, and I’m not sure why as it seems to fulfill the inclusion criteria (trained athletes, double-blind randomized controlled with a placebo group and included all those measurements of strength and body composition). Either way, no one should believe these results from Wilsons study for a second. For one, it was sponsored by Metabolic Technologies Inc, the supplement company owned by Nissen who sells the stuff (and Nissen is the one who discoverd HMB for this purpose and patented it). Of course, sponsored studies are not necessarily bad, we need them, but it’s something to keep in mind. But most of all, the results were so dramatic that they were very comparable to the results of 600 mg of testosterone enanthate weekly in conjunction with strength training (seriously, they did, if you’d compare the results with the Bhasin trial). Finally, a later trial, also from Wilsons lab, combined HMB with ATP (which I assume is the reason this one didn’t get included in the meta-analysis), demonstrating even more incredible results [4]. These studies by Wilson have lead to quite some critique in the scientific literature [5,6]. Which makes you wonder: how can a meta-analysis not even demonstrate an effect, whereas Wilsons lab, TWICE, demonstrated it to be similarly effective as anabolic steroids. Ha ha.

Completely useless for athletes?

Maybe it still has some use in a very specific situation. HMB has been shown to inhibit muscle protein breakdown in an insulin-independent manner [7]. This might make it interesting for people who apply prolonged periods of fasting (as in intermittent fasting), since then insulin is very low (usually insulin after a meal strongly inhibits MPB by about 50%). But this is just pure speculation, as I don’t know of any clinical trial investigating this.

Conclusion: keep your money in your pocket and don’t waste it on HMB.


  1. Sanchez-Martinez, Javier, et al. “Effects of beta-hydroxy-beta-methylbutyrate supplementation on strength and body composition in trained and competitive athletes: A meta-analysis of randomized controlled trials.” Journal of science and medicine in sport (2017).
  2. Zanchi, Nelo Eidy, et al. “HMB supplementation: clinical and athletic performance-related effects and mechanisms of action.” Amino acids 40.4 (2011): 1015-1025.
  3. Wilson, Jacob M., et al. “The effects of 12 weeks of beta-hydroxy-beta-methylbutyrate free acid supplementation on muscle mass, strength, and power in resistance-trained individuals: a randomized, double-blind, placebo-controlled study.” European journal of applied physiology 114.6 (2014): 1217-1227.
  4. Lowery, Ryan P., et al. “Interaction of beta-hydroxy-beta-methylbutyrate free acid and adenosine triphosphate on muscle mass, strength, and power in resistance trained individuals.” The Journal of Strength & Conditioning Research 30.7 (2016): 1843-1854.
  5. Hyde, Parker N., Kristina L. Kendall, and Richard A. LaFountain. “Interaction of Beta-Hydroxy-Beta-Methylbutyrate Free Acid and Adenosine Triphosphate on Muscle Mass, Strength, and Power in Resistance-Trained Individuals.” The Journal of Strength & Conditioning Research 30.10 (2016): e10-e11.
  6. Gentles, Jeremy A., and Stuart M. Phillips. “Discrepancies in publications related to HMB-FA and ATP supplementation.” Nutrition & metabolism 14.1 (2017): 42.
  7. Wilkinson, D. J., et al. “Effects of leucine and its metabolite β‐hydroxy‐β‐methylbutyrate on human skeletal muscle protein metabolism.” The Journal of physiology 591.11 (2013): 2911-2923.

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