HMB (β-hydroxy β-methylbutyrate)

Summary

HMB (β-hydroxy β-methylbutyrate) is a leucine metabolite involved in muscle preservation and recovery.
It helps reduce muscle protein breakdown and may promote modest strength and lean mass gains, particularly in beginners, older adults, or during caloric restriction.

🟢 What It Does (Strong Evidence)

• Helps reduce muscle breakdown (anti-catabolic effect).
• May support lean mass and strength in untrained individuals or seniors.
• Improves recovery after intense training (reduces DOMS and CK levels).
• Beneficial under catabolic conditions (injury, immobilization, calorie deficit).

🟡 What’s Unclear (Gray Areas)

• In trained athletes, effects are usually minimal or absent.
• Bioavailability and form (Ca-HMB vs free acid) can influence effectiveness.
• Few benefits demonstrated beyond 3 g/day.

🔴 What It Doesn’t Do

• Does not replace dietary protein or leucine.
• Does not build muscle without proper training or nutrition.
• Is not a fat burner or energy booster.

Intake & Dosage (Non-prescriptive)

• Typical dose: 3 g/day (often 1 g × 3).
• Take with meals or around workouts.
• Can be combined with creatine or protein for best results.
• Especially relevant for seniors, low-calorie diets, or recovery periods.

💣 Upper Limit (UL)

Note: The standard safe dose is $3 g/day (safe standard dose).
No toxicity reported at this dose.
Long-term studies show no adverse liver or kidney effects, but no added benefit above 3 g/day.

Safety

• Very well tolerated, even with long-term use.
• Occasional mild digestive discomfort reported.
• No known contraindications.

Risks & Interactions

• Generally well tolerated; rare mild digestive discomfort.
• Relevance should be assessed if total protein intake is already optimal.
• No major interactions known at standard doses.
• Can be combined with creatine or protein depending on training goals.

Quality Tips

• Choose pure HMB forms (Ca-HMB or HMB free acid) without additives.
• Verify actual dosage (3 g/day) per serving on the label.
• Effective stack: HMB + Creatine + Protein for enhanced recovery.
• Avoid exaggerated “anabolic” marketing claims.

Sources

• Examine.com — HMB Overview
• PubMed — Clinical studies on strength, sarcopenia, and recovery