Amino Acid ·Moderate evidence ·Reviewed May 2026
Metabolite of leucine that reduces muscle protein breakdown.
The bottom line
Evidence rating moderate. Most-documented uses: muscle preservation, recovery, strength. 21 sources indexed (2004–2025), with 4 interaction records on file.
Core mechanism
Inhibits the ubiquitin-proteasome pathway responsible for muscle protein degradation. Also stimulates mTOR pathway and enhances muscle protein synthesis.18,19
Split doses with meals; free acid form 30 min before exercise1,2
Dosing protocol
Can be used continuously during high-volume training or recovery periods.
Ranked by evidence and value.
Real-world pricing across three quality tiers. Assumes Calcium HMB.
Assumes 3 g/day split dosing. Vendor basis: BulkSupplements powder, NOW Sports/iHerb, Vitacost, and Amazon marketplace; free-acid HMB products price premium. Updated 2026-05-28.
How much you'd eat to match a supplemental dose.
A practical food equivalent for HMB does not exist; HMB is also made in small amounts from leucine.
What to test, the optimal window inside the conventional range, and how long a response takes.
HMB (3 g per day) may attenuate post-exercise CK rise and indices of muscle damage in untrained individuals; effect is smaller in trained athletes.18
Use CK alongside myoglobin and subjective soreness ratings. HMB's clearest evidence is in elderly sarcopenia, where DXA lean mass is a slower endpoint.
Where this appears in the symptom-to-supplement map, ranked by relevance.
HMB, a leucine metabolite, may slow muscle protein breakdown and help preserve lean mass during aging or periods of low activity.6,12
Most relevant for older or deconditioned individuals rather than already-trained athletes.
HMB can help reduce muscle protein breakdown during high training load or inactivity.9,5
Most relevant during intense blocks or return-to-training periods.
HMB attenuates exercise-induced muscle damage and supports recovery in untrained adults; effect in trained athletes is smaller.5,1
Largest effect in elderly sarcopenia and detraining periods.
Evidence-based stacks that include it, with the exact dose and timing each one uses.
HMB, a metabolite of leucine, may attenuate muscle protein breakdown and could support recovery during periods of intense training or caloric restriction; evidence is mixed and benefits in well-trained, well-fed athletes appear small.18,7
HMB (a metabolite of leucine) has been studied for reducing muscle protein breakdown, with the most relevant evidence during periods of muscle stress such as a caloric deficit or detraining. Results are mixed, so it is best viewed as an adjunct to sufficient dietary protein, and benefit is unlikely if total protein intake is already adequate.7
HMB is a leucine metabolite that may help attenuate muscle protein breakdown, and it has shown the most promise for preserving lean mass during periods of bed rest or inactivity in older adults. Evidence in healthy, actively training older adults is mixed, so it is considered emerging here.18,7
Complementary effects on lean mass and strength, with creatine enhancing high-intensity performance and HMB reducing muscle protein breakdown.
Recommendation: Reasonable to combine as part of a resistance-training and protein-adequate program; no timing separation required.
Vitamin D supports muscle function and the response to HMB, with combined supplementation showing greater gains in muscle strength and quality, particularly in older or deficient adults.
Recommendation: Reasonable to combine, especially if vitamin D status is low; check and correct vitamin D levels for best muscle response.
HMB is a metabolite of leucine, so BCAAs and HMB act on related anabolic and anti-catabolic pathways to support muscle protein balance.
Recommendation: Combining is reasonable around training, though the benefit overlaps since HMB derives from leucine; prioritize total protein intake first.
Beta-alanine combined with HMB has shown additive benefits for lean mass and performance in training studies.
Recommendation: May be combined as part of a training regimen without special timing.
Numbered references. Citations throughout the page link here.
In 5 RCTs, HMB supplementation showed beneficial effect on skeletal muscle mass index (SMD 0.32, P=0.048) and handgrip strength (SMD 0.65, P=0.034), but no evidence of benefit on physical performance measured by gait speed.
Sadeghi B, Bahari H, Jozi H et al.. Effects of β-hydroxy-β-methylbutyrate (HMB) supplementation on lipid profile in adults: a GRADE-assessed systematic review and meta-analysis of randomized controlled trials. Frontiers in nutrition. 2024
Su H, Zhou H, Gong Y et al.. The effects of β-hydroxy-β-methylbutyrate or HMB-rich nutritional supplements on sarcopenia patients: a systematic review and meta-analysis. Frontiers in medicine. 2024
Feng Y, Chen P, Li T et al.. Effects of exercise with or without β-hydroxy-β-methylbutyrate supplementation on muscle mass, muscle strength, and physical performance in patients with sarcopenia: a systematic review and meta-analysis. Frontiers in nutrition. 2024
In 9 RCTs with 896 subjects, HMB supplementation had a statistically significant overall impact on muscle strength-related indicators (SMD 0.41, 95% CI 0.28-0.54, p<0.00001) in the elderly population.
15 RCTs with 2,137 patients showed some evidence supporting HMB for increasing skeletal muscle mass and strong evidence for improving muscle strength.
Rahimi MH, Mohammadi H, Eshaghi H et al.. The Effects of Beta-Hydroxy-Beta-Methylbutyrate Supplementation on Recovery Following Exercise-Induced Muscle Damage: A Systematic Review and Meta-Analysis. Journal of the American College of Nutrition. 2018
Silva VR, Belozo FL, Micheletti TO et al.. β-hydroxy-β-methylbutyrate free acid supplementation may improve recovery and muscle adaptations after resistance training: a systematic review. Nutrition research (New York, N.Y.). 2017
Seven RCTs with 287 older adults showed HMB supplementation contributed to greater muscle mass preservation compared to controls.
Molfino A, Gioia G, Rossi Fanelli F et al.. Beta-hydroxy-beta-methylbutyrate supplementation in health and disease: a systematic review of randomized trials. Amino acids. 2013
HMB is effective in preventing exercise-related muscle damage in both trained and untrained individuals during resistance training.
Ogawa M, Satomi-Kobayashi S, Yoshida N et al.. Effects of preoperative beta-hydroxy-beta-methylbutyrate, arginine, and glutamine supplementation on cardiac surgery: A randomized controlled trial. Clinical nutrition (Edinburgh, Scotland). 2025
At 50 micromol/L concentration, HMB completely attenuated PIF-induced protein degradation and induction of the ubiquitin-proteasome proteolytic pathway.
HMB inhibits ubiquitin-proteasome protein degradation, decreases cell apoptosis, stimulates mTOR-mediated protein synthesis, and enhances GH/IGF-1 axis and muscle stem cell proliferation.
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