Benefits of HMB (Beta-Hydroxy Beta-Methylbutyrate)

Evidence-Based Benefits

• Lean mass — Nissen & Sharp (2003) meta-analysis of 9 studies found 3 g/day HMB increased lean mass by 0.28% per week and strength by 1.40% per week vs placebo in resistance-trained subjects
• Anti-catabolic — HMB inhibits the ubiquitin-proteasome proteolytic pathway, the primary mechanism for muscle protein degradation during stress, catabolism, and disuse
• Muscle preservation during caloric deficit — Wilkinson et al. (2013) found HMB attenuated muscle loss during energy restriction combined with exercise, making it valuable during cutting phases
• Sarcopenia prevention — Wu et al. (2015) meta-analysis found HMB supplementation preserved muscle mass and improved physical function in older adults

What the Research Says

HMB is best understood as an anti-catabolic supplement rather than an anabolic one. It works primarily by reducing muscle protein breakdown, which makes it most valuable in situations of high catabolic stress: untrained individuals experiencing novel training stimulus, caloric restriction, aging, and prolonged bed rest. The Nissen & Sharp (2003) meta-analysis established its efficacy, though subsequent studies in trained athletes have shown more modest benefits. A controversial 2014 study (Wilson et al.) showed dramatic results that have not been replicated and are widely questioned. For trained athletes already consuming adequate protein, the incremental benefit of HMB is small.

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