HMB (Beta-Hydroxy Beta-Methylbutyrate)
A genuine muscle-preservation niche in older adults, sold to young lifters where it does nothing measurable.
C
Evidence grade
C-
Worth it
$20-35/month
Typical cost
DoseThe studied dose is 3 g/day of calcium HMB (or about 2.4 g of the free-acid form), split across the day. Context that decides value: adequate total protein (this library's graded target is roughly 1.6 g/kg/day for muscle goals) already supplies leucine far beyond what 3 g of its metabolite adds, which is the mechanistic explanation for the null results in fed, trained people.
BasisHMB is a real anti-catabolic with a real niche and an inflated reputation outside it.
HMB is a metabolite of leucine, the amino acid that triggers muscle protein synthesis. We grade HMB (Beta-Hydroxy Beta-Methylbutyrate) C on evidence and C- for worth-it at about $20-35 per month.
What it does
HMB is a metabolite of leucine, the amino acid that triggers muscle protein synthesis. It is sold as an anti-catabolic: a compound that slows muscle breakdown rather than building muscle directly. Its record splits sharply by who is taking it, and this record is written in two voices accordingly.
What the research says
Preserves lean mass modestly in older adults and clinical populations, where muscle is actually being lost
Evidence: emerging. Meta-analyses in adults over 60 and in catabolic settings (Wu 2015 and successors) find HMB modestly improves or preserves lean mass, with functional effects less consistent. This is the use the evidence supports: defending muscle in people whose physiology is spending it, during aging, illness, or enforced inactivity.
In healthy young people who train, added benefit is negligible in rigorous meta-analysis
Evidence: moderate. HMB's fame came from 1990s studies in novices. Meta-analyses restricted to trained lifters (Rowlands and Phillips 2011 and later poolings) find effects on lean mass and strength at or near zero once training and protein are accounted for. The supplement works where its mechanism has something to fix (excess breakdown) and vanishes where breakdown is not the limiting factor.
HMB is a real anti-catabolic with a real niche and an inflated reputation outside it. In older adults and wasting conditions it earns modest credit; in the young trained market that buys most of it, rigorous pooling finds nothing. C averages those two truths with the niche weighted, because the niche is where a reader could actually benefit.
Is it worth it?
Evidence (C) sits below the leaderboard floor, so the worth-it grade is capped at C+; the derived value lands at C-, because 3 g/day of HMB is not cheap and its best-supported use is narrow. About $27 a month. Derived from the October 2026 worth-it model.
Typical cost
$20-35/month
Common form, not a brand recommendation
Dosage context established
The studied dose is 3 g/day of calcium HMB (or about 2.4 g of the free-acid form), split across the day. Context that decides value: adequate total protein (this library's graded target is roughly 1.6 g/kg/day for muscle goals) already supplies leucine far beyond what 3 g of its metabolite adds, which is the mechanistic explanation for the null results in fed, trained people.
Worth-it leaderboard
HMB (Beta-Hydroxy Beta-Methylbutyrate) sits outside the worth-it top 20.
HMB (Beta-Hydroxy Beta-Methylbutyrate) sits outside the current top 20 on the gated leaderboard. The leaders below clear an evidence floor of B- before price counts at all, so cheap alone never earns a rank.
- 1AWorth itCreatine evidence A-~$5-10/mo
- 2AWorth itCaffeine evidence B+~$5-10/mo
- 3AWorth itVitamin D evidence B~$5-8/mo
See the full worth-it leaderboard →
When the evidence moves a grade, this ranking moves with it. Thursday is where you hear it first.
Safety notes
Well tolerated in trials at 3 g/day for months; occasional GI upset. Long-term data beyond a year are limited. No significant interactions documented. The risk profile is benign; the budget profile is the issue, priced below.
Longevity Lab Report
HMB (Beta-Hydroxy Beta-Methylbutyrate) news. Graded when it happens.
The grade on this page stays free. The email carries the news on hmb (beta-hydroxy beta-methylbutyrate): expert moves, dose changes, and what is working, in plain English every Thursday.
Changelog
Last updated 2026-10-23
- 2026-10-23|Graded from the population-split meta-analytic record: positive-to-neutral in older and clinical groups, null in trained young lifters. The record addresses both audiences separately because averaging them produced thirty years of confused marketing.
- 2026-10-23|Listed under muscle, matching this record's graded findings in older adults.
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This grade for HMB (Beta-Hydroxy Beta-Methylbutyrate) rests on the record above. When a new result changes that record, the grade changes with it, and the Thursday email is where the change lands first: the week's longevity and biohacking news, in plain English, linked back to the reasoning on this page.
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