HMB: A Lesser-Known Muscle Preservation Supplement Worth Knowing About

What HMB actually is

A metabolite of the amino acid leucine, HMB (beta-hydroxy beta-methylbutyrate) has shown some evidence for reducing muscle protein breakdown, particularly in situations of muscle loss risk.

Where the evidence is strongest

Older adults at risk of age-related muscle loss, and people in periods of significant physical stress (illness, aggressive calorie deficits, immobilization) show the clearest benefit in research, more so than healthy, actively training younger adults.

Why it's less relevant for the average gym-goer

For a healthy adult already eating sufficient protein and training consistently, HMB's additional benefit on top of that foundation appears modest at best — the populations where it shows clearest benefit are somewhat specific.

A reasonable way to think about it

Worth considering for older adults, those recovering from significant muscle-wasting illness, or anyone in an aggressive cutting phase specifically concerned about muscle preservation — not a default addition for general fitness goals.