Strength & Power
HMB (β-Hydroxy β-Methylbutyrate)
A leucine metabolite with anti-catabolic properties. Effect is significant only in untrained individuals or during caloric deficits.
Effective Dose
3g / day
per clinical evidence
Evidence Level
Limited
Strength & Power
Mechanism
Protein degradation inhibition
primary action
Best For
Beginners
Cutting phases, Injury recovery
This profile is for informational purposes only and does not constitute medical advice. Consult a qualified healthcare professional before starting any supplementation, especially if you have pre-existing conditions or take medications.
What Is HMB (β-Hydroxy β-Methylbutyrate)?
HMB is produced in the body from leucine via α-keto-isocaproate. It inhibits the ubiquitin-proteasome pathway of protein degradation, reducing muscle breakdown. Benefits are most pronounced in populations with high rates of muscle catabolism — beginners, those in caloric deficits, or during immobilisation.
How It Works: The Science
HMB inhibits the ubiquitin-proteasome proteolytic pathway, the primary mechanism by which muscle protein is degraded under catabolic conditions. It also activates mTOR (like leucine) to promote protein synthesis, though this is a weaker effect than HMB's anti-catabolic action. HMB-FA (free acid form) is absorbed faster than calcium HMB.
Primary Mechanism
Protein degradation inhibition
Evidence-Based Benefits
Dosage Guide
Effective Dose
3g / day
3g/day split across two or three doses. HMB calcium salt is the most studied form. HMB-FA (free acid) absorbs faster and may be more acutely effective pre-workout. Effects are modest — do not expect creatine-level results.
Safety Profile & Side Effects
Well tolerated with no significant adverse effects reported across multiple trials. Safe in older adults and in populations with liver and kidney disease at standard doses.
Who Should (and Shouldn't) Take It
Untrained beginners in the first 3–6 months of training, athletes in significant caloric deficits, elderly populations preventing sarcopenia, and those recovering from injury or surgery. Poor value for experienced, well-fed strength athletes.
Frequently Asked Questions
Related Ingredients
Medical Disclaimer
Ingredient profiles are for informational purposes only and do not constitute medical advice. Consult a qualified healthcare professional before starting any supplementation, especially if you have pre-existing conditions or take medications. Full disclaimer →