HMB (β-hydroxy β-methylbutyrate)
Sleep & Recovery · Leucine metabolite
Tier B+
Bottom line
Read Off Label grades HMB (β-hydroxy β-methylbutyrate) as B+ (7.2/10) based on moderate evidence, low-med benefit magnitude, and a very low-risk safety profile.
Most useful when muscle loss is the concern (age-related sarcopenia, bed rest, training novices) rather than when maximizing gains in trained lifters.
Typical use: 3 g/day PO divided (commonly 1 g 3x/day); calcium HMB or free-acid HMB — OTC.
What this is
Most useful when muscle loss is the concern (age-related sarcopenia, bed rest, training novices) rather than when maximizing gains in trained lifters. Wilson 2013 ISSN position stand is the standard reference. Free-acid form better absorbed than calcium HMB.
Mechanism
Downstream metabolite of leucine (~5% of leucine converts to HMB); upregulates mTORC1, downregulates proteasomal/autophagic protein breakdown; anti-catabolic more than anabolic
Dose & route
3 g/day PO divided (commonly 1 g 3x/day); calcium HMB or free-acid HMB
Citations
- https://pubmed.ncbi.nlm.nih.gov/23374455/
- https://pubmed.ncbi.nlm.nih.gov/23924954/
- https://pmc.ncbi.nlm.nih.gov/articles/PMC3568064/
- https://doi.org/10.1177/21621918261444178
- https://doi.org/10.1097/mcc.0000000000001386
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Common questions
- Does HMB (β-hydroxy β-methylbutyrate) work?
- Read Off Label rates the evidence for HMB (β-hydroxy β-methylbutyrate) as Moderate and the benefit magnitude as low-med, producing an overall grade of B+ (7.2/10). Most useful when muscle loss is the concern (age-related sarcopenia, bed rest, training novices) rather than when maximizing gains in trained lifters.
- Is HMB (β-hydroxy β-methylbutyrate) safe?
- HMB (β-hydroxy β-methylbutyrate) has a very low risk profile in published human data. Legal status: OTC. This is not medical advice — see the disclaimer.
- What is the typical dose for HMB (β-hydroxy β-methylbutyrate)?
- 3 g/day PO divided (commonly 1 g 3x/day); calcium HMB or free-acid HMB
- How does HMB (β-hydroxy β-methylbutyrate) work?
- Downstream metabolite of leucine (~5% of leucine converts to HMB); upregulates mTORC1, downregulates proteasomal/autophagic protein breakdown; anti-catabolic more than anabolic
This is an independent synthesis of published research by a non-clinician. Scores are opinions supported by citations, not prescriptions. See the full disclaimer and methodology for how this score was produced and what it does and doesn't mean.