HMB: Does It Deliver on Its Muscle-Building Promise?
If you’re wanting to build muscle (and many triathletes do), you’ve probably heard about β-hydroxy-β-methylbutyrate, or HMB. It’s often touted as a supplement that builds muscle, burns fat, and boosts strength during resistance training. But is HMB really a game-changer, or is it just another overhyped product?
Let’s take a closer look.
What Is HMB?
HMB is a byproduct of leucine, an essential amino acid known to support muscle protein synthesis. While HMB has been shown to stimulate protein production in lab settings (think petri dishes), the big question is whether it can deliver noticeable results in humans.
The Latest Research on HMB
A recent meta-analysis by Jakubowski et al dug deep into 11 double-blind clinical trials to evaluate HMB’s actual effects. Here’s what they discovered:
->Body Weight
HMB users gained a little more weight than those taking a placebo—about 0.34 kg (just under a pound). However, this modest difference was influenced by one standout study conducted by HMB’s patent holder. When that study was removed, the weight gain vanished.
->Lean Body Mass
The HMB group gained an average of 1.57 kg (about 3.5 pounds) of lean body mass compared to 1.17 kg in the placebo group. While this difference might sound promising, it’s just a few hundred grams—hardly transformational.
->Fat Loss
Despite its reputation, HMB didn’t outperform the placebo when it came to fat loss. Both groups lost about the same amount of fat.
->Muscle Strength
The numbers for strength gains were almost identical. For instance, people taking HMB improved their one-rep max (1RM) by 32.0 kg, while the placebo group gained 30.6 kg. That’s a difference of just 1.4 kg—not statistically significant.
Extraordinary Claims, Questionable Results
Some studies have reported jaw-dropping muscle gains—up to 9.3 kg (more than 20 pounds) of lean mass in 12 weeks. But these results were so far outside the normal range that they were excluded from the meta-analysis. Gains like this are typically seen only with anabolic steroids, raising questions about the reliability of those findings.
Should You Consider HMB?
While HMB does activate pathways that promote muscle protein synthesis, there’s little evidence to suggest it’s more effective than leucine itself or leucine-rich foods like high-protein meals. The meta-analysis concluded that HMB might provide a slight boost in body weight but doesn’t significantly improve lean mass, fat loss, or strength during resistance training.
The Bottom Line
If you’re looking for a supplement to give you an edge, HMB might offer some minor benefits—but don’t expect miracles. A well-rounded diet with plenty of protein, paired with consistent resistance training, is still your best bet for building muscle and strength.
References
Jakubowski et al. Supplementation with the Leucine metabolite hydroxy-methylbutyrate (HMB) does not Improve Resistance Exercise-Induced Changes in Body Composition or Strength in Young Subjects: A Systematic Review and Meta-Analysis Nutrients 12, 1523, 2020.
Kraemer, W.J.; Hatfield, D.L.; Volek, J.S.; Fragala, M.S.; Vingren, J.L.; Anderson, J.M.; Spiering, B.A. Thomas, G.A.; Ho, J.Y.; Quann, E.E.; et al. Effects of amino acids supplement on physiological adaptations to resistance training. Med. Sci. Sports Exerc. 41, 1111–1121, 2009.
Wilson, J.M.; Lowery, R.P.; Joy, J.M.; Andersen, J.C.; Wilson, S.M.; Stout, J.R.; Duncan, N.; Fuller, J.C.; Baier, S.M.; Naimo, M.A.; et al. The e_ects 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. Eur. J. Appl. Physiol. 114, 1217–1227, 2014.
Lowery, R.P.; Joy, J.M.; Rathmacher, J.A.; Baier, S.M.; Fuller, J.C., Jr.; Shelley, M.C., 2nd; Jager, R.; Purpura, M.; Wilson, S.M.; Wilson, J.M. Interaction of Beta-Hydroxy-Beta-Methylbutyrate Free Acid and Adenosine Triphosphate on Muscle Mass, Strength, and Power in Resistance Trained Individuals. J. Strength Cond. Res. 30, 1843–1854, 2016.
Wilkinson, D.J.; Hossain, T.; Hill, D.S.; Phillips, B.E.; Crossland, H.; Williams, J.; Loughna, P. Churchward-Venne, T.A.; Breen, L.; Phillips, S.M.; et al. Effects of leucine and its metabolite beta-hydroxy-beta-methylbutyrate on human skeletal muscle protein metabolism. J. Physiol. 591, 2911–2923, 2013.
Jakubowski, J.S.;Wong, E.P.T.; Nunes, E.A.; Noguchi, K.S.; Vandeweerd, J.K.; Murphy, K.T.; Morton, R.W.; McGlory, C.; Phillips, S.M. Equivalent Hypertrophy and Strength Gains in beta-Hydroxy-beta-Methylbutyrate or leucine-supplemented Men. Med. Sci. Sports Exerc. 51, 65–74, 2019.
Nissen, S.; Sharp, R.; Ray, M.; Rathmacher, J.A.; Rice, D.; Fuller, J.C., Jr.; Connelly, A.S.; Abumrad, N. Effect of leucine metabolite beta-hydroxy-beta-methylbutyrate on muscle metabolism during resistance-exercise training. J. Appl. Physiol. 81, 2095–2104, 1996.
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