A compound the body makes from a building block of protein, sold for holding on to muscle. Gains in mass and strength are small but consistent where muscle is actively being lost — older age, illness, surgery, enforced inactivity — and largely absent in already-trained adults. Safety markers show no harm; long-term use is unstudied. (Full Review)
| Marker | Target | Why |
|---|---|---|
| Appendicular lean mass index | Above 7.0 kg/m² in men, 5.5 kg/m² in women | The outcome HMB most directly targets |
| Grip strength | Above 27 kg in men, 16 kg in women | The strength outcome with the most consistent trial support |
| Chair-rise time (five repetitions) | Under 12 seconds | Whole-body functional capacity, the endpoint that matters for independence |
| Walking speed over 4 m | Above 1.0 m/s | Independent predictor of later disability |
| Blood urea nitrogen | 10–18 mg/dL | Detects the nitrogen-load rise seen with HMB-arginine-glutamine products |
| Creatinine and estimated glomerular filtration rate | eGFR above 60 mL/min/1.73 m²; creatinine mid-range for sex | Confirms kidney handling before and during chronic use |
| Serum calcium, albumin-corrected | 9.0–10.0 mg/dL | Tracks the added calcium load from the calcium salt form |
| Fasting glucose and HbA1c | Glucose 75–90 mg/dL; HbA1c under 5.4% | Addresses the unresolved glucose-handling question raised by rodent work |
| Creatine kinase | 50–200 U/L in the untrained | Quantifies the muscle-damage marker HMB lowers in pooled trials |
| 25-hydroxyvitamin D | 40–60 ng/mL | Identifies the deficiency that was corrected alongside HMB in the longest trial |
| Total daily protein intake | No established blood target; track change from own baseline, aiming at 1.2–1.6 g per kilogram | Establishes whether HMB is being added on top of adequacy or in place of it |
Cadence: Functional measures at 12 weeks, then every 6 months; laboratory markers at 3 months, then annually; body composition every 6 to 12 months.