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Amino acid

HMB

HMB (beta-hydroxy-beta-methylbutyrate) is a substance the body makes from the amino acid leucine. It is mostly studied for muscle preservation.

Also listed as Hydroxy-MethylButyrate, beta-hydroxy-beta-methylbutyrate

FitnessEnergy

What it is studied for

The strongest rated effects first. Bars show the size of the effect, the letter grades the evidence, and each rating lists the studies behind it.

Muscle RecoveryFitnessModerateA3 studies
Strength TrainingFitnessModerateB3 studies
Injury PreventionFitnessModerateBNo linked study
Physical EnergyEnergySmallCNo linked study
Endurance and staminaFitnessNo effectFNo linked study
Every rating with its studiesGrouped by health goal, with the publications behind each rating

What is HMB supposed to change?

HMB is a substance the body makes from the amino acid leucine. Researchers have proposed that it could support protein synthesis, reduce protein breakdown and help repair muscle-cell membranes. These mechanisms explain the interest in muscle preservation; they do not guarantee extra strength from a supplement. 1

Key studies

The most recent publications linked to HMB's ratings.

Ergogenic Benefits of β‐Hydroxy‐β‐Methyl Butyrate (HMB) Supplementation on Body Composition and Muscle Strength: An Umbrella Review of Meta‐Analyses2025Effects of β-hydroxy-β-methylbutyrate supplementation on recovery from exercise-induced muscle damage: a mini-review2022Supplementation with the Leucine Metabolite β-hydroxy-β-methylbutyrate (HMB) does not Improve Resistance Exercise-Induced Changes in Body Composition or Strength in Young Subjects: A Systematic Review and Meta-Analysis2020The Effects of Beta-Hydroxy-Beta-Methylbutyrate Supplementation on Recovery Following Exercise-Induced Muscle Damage: A Systematic Review and Meta-Analysis2018β-hydroxy-β-methylbutyrate free acid supplementation may improve recovery and muscle adaptations after resistance training: a systematic review.2017
All 6 studiesEvery publication linked to HMB

Why people take it

Fitness23.5%
Bone & Joint19%
Essential Health17.5%
Energy12.5%
Weight Management8.5%
Immune Support7.5%

SuppCo community snapshot, 2026-09-28. Reasons for use are not evidence that it works.

Questions people ask

Is HMB the same as leucine?

No. HMB is produced from leucine; NIH estimates that about 5% of leucine is converted to HMB. 1

Does free-acid HMB work better?

It enters the bloodstream faster, but superiority for training outcomes remains unclear. 1

Are the recovery findings purely theoretical?

No. Human trials found changes in blood markers, but those markers do not directly measure restored performance. 2

Sources