Calculate HMB (β-hydroxy β-methylbutyrate) dose. Leucine metabolite (about 5% of leucine converts to HMB). Anti-catabolic — most useful in elderly sarcopenia, bed rest/immobilization, caloric deficit, untrained beginners. Diminishing returns in trained athletes. Math, not medical advice.
Your situation
3
g HMB per day, split 3 × 1g
g HMB per day, split 3 × 1g
Mechanism and what HMB actually does
- Anti-catabolic: reduces protein breakdown (mTOR-independent pathway). This is the dominant effect.
- Mildly anabolic: some effect on protein synthesis, but smaller than full leucine/EAA dosing.
- Cell membrane repair: HMB is a precursor to cholesterol → membrane integrity → reduced muscle damage.
- Why elderly + cutting + bed rest: all are contexts of HIGH protein breakdown. HMB has more room to work.
- Why trained athletes see less: already adapted, protein synthesis is maximal, HMB has little additional headroom.
Form comparison: Ca-HMB vs HMB-FA
- Calcium HMB (Ca-HMB): standard, cheaper, slower absorption (peak ~2 hours). Most clinical trials use this.
- HMB free acid (HMB-FA): faster absorption (peak ~30-60 min), higher peak concentration. Marketed for pre-workout. Smaller evidence base but theoretically better acute effect.
- Practical: Ca-HMB at 3g/day split is the standard. HMB-FA may suit specific pre-workout protocols if cost isn’t an issue.
Stacking
- With protein: doesn’t replace protein. HMB on top of adequate protein (1.6-2.2 g/kg) is the model.
- With creatine: good combo for elderly + sarcopenia (different mechanisms, additive evidence).
- With vitamin D: elderly often deficient; D + HMB + protein = the “anti-sarcopenia trio.”
- With leucine: redundant if leucine intake is adequate (about 3g leucine per meal from protein). HMB doesn’t replace leucine dosing for protein synthesis.
Safety
- Generally well tolerated at 3g/day across multi-year trials.
- Mild GI upset possible (rare).
- Calcium content of Ca-HMB (about 11%) — 3g Ca-HMB = ~330 mg calcium. Factor into bone-stack calcium total.
- Pregnancy/lactation: safety not established; avoid.
