Graded against 178,763 supplements and 757 reviewed supplement and medication pairs, sourced from PubMed, FDA CAERS, openFDA, NIH DSLD
HMB
Amino AcidLast updated
AVELOR SUMMARY
HMB is a metabolite of leucine that prevents muscle protein breakdown (anti-catabolic).
Our research shows its benefits are population-specific: it significantly reduces muscle loss in elderly, bedridden, or calorie-restricted individuals (0.5-1.0 kg lean mass preservation), but in trained athletes with adequate protein intake, the effects are minimal.
A controversial 2014 study claiming HMB outperformed anabolic steroids was widely criticized for methodological issues and has not been replicated.
The free acid form (HMB-FA) is absorbed faster but there's no evidence it produces better long-term outcomes than calcium HMB.
WHAT IT DOES
HMB works primarily by inhibiting the ubiquitin-proteasome pathway, the cellular machinery that breaks down muscle proteins during stress, illness, bed rest, and caloric deficit. It also upregulates mTOR signaling and reduces muscle cell apoptosis. About 5% of dietary leucine is converted to HMB (so 60g of leucine to get 3g HMB from food alone), which is why supplementation is necessary for therapeutic levels. The key insight: HMB is anti-catabolic (prevents breakdown), not anabolic (doesn't build muscle). This is why it works in catabolic states but not in well-fed, well-trained athletes.
OPTIMAL DOSAGE
Look for: HMB-Ca (calcium salt) at 1,000mg per capsule/serving; minimum 3g/day total; branded HMB from TSI Group (patent holder)
Avoid: Products containing leucine claiming HMB benefits (you'd need 60g leucine to make 3g HMB); proprietary blends; under-dosed products (<3g/day)
Minimum effective dose: 3,000mg/day
Third-party tested brands: NOW Foods, BulkSupplements, Optimum Nutrition
No significant drug interactions have been identified in clinical literature. HMB is a naturally occurring metabolite of leucine with no known pharmacological interactions. However, as with any supplement, inform your healthcare provider before combining with prescription medications.
Independently graded against 178,763 indexed supplements and 757 reviewed supplement and medication pairs, sourced from PubMed, FDA CAERS, openFDA, and NIH DSLD | Last updated:
Not medical advice. Based on published clinical research and systematic reviews.