HMB (β-Hydroxy β-Methylbutyrate)
Muscle building & fitnessFunction & benefits
An active metabolite of the amino acid leucine; it helps limit muscle protein breakdown by inhibiting the ubiquitin pathway and stimulating mTOR, and is most useful during calorie restriction and to limit age-related muscle loss.
Dosage & how to use
| Recommended dose | 3 g daily |
| Best time to take | As one dose 60 minutes before training, or 1 g with each main meal |
| Frequency | Once daily or split over 3 meals |
Best forms to choose
Calcium HMB (HMB-Ca), the most common and affordable form, and free-acid HMB (HMB-FA), which reaches the blood faster.
Important warnings
Safe for long-term use up to 3 g a day
Adds little for people already eating plenty of whey protein and leucine
People with kidney failure should consult a doctor, as HMB-Ca contains calcium
Drug interactions
No serious clinical drug interactions have been reported.
Related supplements
- Whey ProteinMuscle building & fitness
- Casein ProteinMuscle building & fitness
- Creatine MonohydrateMuscle building & fitness
- BCAA (Branched-Chain Amino Acids)Muscle building & fitness
Scientific references
- Wilson JM et al. ISSN Position Stand: HMB. J Int Soc Sports Nutr 2013 — PMID: 23374455
Content last updated: 17 October 2026 · Based on published sources and research (EFSA / NIH / PubMed)
⚖️ Medical disclaimer: The information and data provided here are for health education and nutritional guidance only. They are not a medical diagnosis and never replace a direct consultation with your doctor or pharmacist. Always consult your doctor before starting any supplement, especially during pregnancy or breastfeeding or when taking long-term medication.