Mobility/Weight/Performance

HMB

Leucine metabolite that may help preserve muscle and physical function, especially in older adults or during inactivity.

HMB

Leucine metabolite that may help preserve muscle and physical function, especially in older adults or during inactivity.

score

evidence

Safe

risk

Proven Benefits

01Preserves lean mass

02May improve physical function

03May reduce muscle damage

04May improve strength gains

05May improve body composition

06May improve aerobic performance

Chemical Forms

Recommended

Calcium HMB
HMB free acid

Avoid

Expert Note

Calcium HMB has the most clinical data and is the default evidence-based choice. HMB free acid reaches the bloodstream faster and may fit pre-workout use, but long-term outcomes are not clearly superior. Choose products that disclose the exact HMB form and daily dose.

Protocol

Amount

3 g

Frequency

Split into 2-3 doses daily

When

Any time of day — consistency matters more than timing; HMB free acid can be taken 30-60 minutes pre-workout.

Condition-Based Dosing

Adults 50+ or during reduced activity

3 g daily for 8-12 weeks— Works best with adequate protein and some resistance or mobility work when possible.

Starting resistance training

3 g daily, often as 1 g three times daily— Most clinical studies use calcium HMB rather than free acid.

Using HMB free acid around workouts

1-3 g 30-60 minutes pre-workout, keeping total daily intake near 3 g— Faster absorption does not clearly outperform daily calcium HMB over time.

Safety & Limits

Upper Safe Limit

No official UL established; 3 g/day is the standard studied dose, and up to 6 g/day has been used short term in adult studies without major adverse effects.

Cycling

Safe for continuous use

Contraindications

Pregnancy or breastfeeding — insufficient safety data

Severe kidney disease — limited long-term safety data; use medical supervision

Severe liver disease — limited safety data; use medical supervision

Synergies

Vitamin D3

Low vitamin D status can worsen muscle function; combined HMB plus vitamin D has shown better muscle outcomes in some older-adult trials.

Whey protein

Protein supplies essential amino acids for synthesis while HMB helps reduce breakdown, making lean-mass retention more likely.

Avoid Combining With

✕Very low protein intake (limits muscle-preserving effect)
✕Heavy alcohol use (impairs muscle protein synthesis and recovery)
✕Complete inactivity when rehab is possible (smaller effect on strength/function)

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