HMB (β-Hydroxy β-Methylbutyrate)
A leucine metabolite that reduces muscle breakdown. Most useful in catabolic states — illness, aggressive caloric restriction, older adults losing lean mass.
Moderate for muscle preservation in catabolic states (older adults, aggressive cutting, post-injury). Modest in healthy trained adults. Effects: 4–12 weeks.
Make it part of your plan
Reference dose
3 g/day, split into 1 g doses across the day.
Choose a stack first, or enter your own amount here. Reference information is not a personal prescription.
HMB is a metabolite of the branched-chain amino acid leucine. The body produces a small amount; supplementation raises levels meaningfully. Its primary effect is anti-catabolic — reducing muscle protein breakdown. Most useful in catabolic contexts: aggressive cutting / dieting, post-injury recovery, older adults losing lean mass (sarcopenia), critical illness recovery, and aggressive training phases. Less impressive in young, well-fed, recreationally training adults (creatine outperforms it for muscle building in healthy users).
- Form
- HMB free acid (faster absorption) or HMB calcium (cheaper, slower).
- Timing
- With meals, split throughout the day. Pre-workout for training days.
- Schedule
- Daily during catabolic phases or aggressive cutting.
- Side effects
- Generally very well-tolerated. Mild GI upset rare.
- Interactions
- Generally clean.
- Contraindications
- None significant.
- Lab markers
- Body composition, lean mass tracking.
- Food sources
- Trace amounts in grapefruit, alfalfa, catfish — far below supplemental doses.
Pairs with
Creatine, protein, vitamin D3 (muscle preservation stack). Beta-alanine for combined performance.
Where to buy
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within Amino acids & derivatives