Amino acids & related
HMB
Names you may see: beta hydroxy beta methylbutyrate calcium HMB HMB free acid
The quick take
HMB is a compound the body makes from leucine.
A closer look
What forms will I see on a label?
Available as calcium HMB or HMB free acid. These forms differ; check the declared HMB amount.
Why people use it
Marketed for muscle preservation, recovery and strength.
These are common goals and marketing uses. The evidence section below explains what research supports.
What does the evidence tell us?
Training studies give mixed results. Benefits may depend on training status and exercise demands; results are not guaranteed for experienced lifters.
What should I know before using it?
Short-term adult studies are reassuring, but long-term safety is less established. Calcium HMB also contributes calcium.
Sources & further reading
NIH Office of Dietary Supplements ↗
Content reviewed: September 30, 2026
General educational information. Follow the product label and seek individual advice when needed.