HMB (Beta-Hydroxy Beta-Methylbutyrate)
Also known as: beta-hydroxy beta-methylbutyrate, HMB-Ca, HMB-FA, calcium HMB, myHMB
A metabolite of leucine studied for reducing exercise-induced muscle protein breakdown and supporting strength and lean mass, particularly in untrained people, older adults, and during intense training blocks. The calcium salt (HMB-Ca) is the common powder and capsule form; the free-acid gel (HMB-FA) is absorbed faster. The ISSN position stand endorses 3 g/day taken consistently.
Research summary
Reduces muscle protein breakdown via the ubiquitin-proteasome pathway and stimulates protein synthesis through mTOR.
Dosage
Daily amounts, of compound.
| Lowest studied | Typical range | Highest studied | Upper limit |
|---|---|---|---|
| 1.5 g | 3 g | 6 g | — |
3 g/day (about 38 mg/kg), split into 1 g doses, is the ISSN-recommended intake; 1.5 g/day produced smaller effects and 6 g/day added no further benefit. HMB-Ca should be taken 60–120 minutes before training, HMB-FA 30–60 minutes before. Effects require two or more weeks of daily use.
Source material: synthetic (calcium salt or free acid)
As supplied: HMB-Ca supplies about 80% HMB by mass plus roughly 13% calcium.
Format suitability
- Capsule
- Powder
- Tablet
- Softgel
- Gummy
- Liquid
HMB-Ca is chalky and bitter; a 3 g daily dose is about four size-00 capsules or 3–4 tablets, so powders and multi-unit servings are typical. HMB-FA is a viscous liquid or gel format.
Formulation notes
Pairs with creatine for additive strength support and with vitamin D3 in older-adult muscle formulas. Count the calcium from HMB-Ca toward total calcium.
Sources
Related ingredients
Creatine Monohydrate
Sports performanceThe most researched sports supplement in existence.
Typical: 3–5 g
Essential Amino Acid (EAA) Blend
Sports performanceA free-form blend of all nine essential amino acids, typically leucine-weighted, that provides the complete substrate for muscle protein synthesis without the bulk of a full protein serving.
Typical: 6–15 g
L-Leucine
Amino acidThe branched-chain amino acid that most directly triggers muscle protein synthesis through mTOR signaling.
Typical: 2.5–5 g
Whey Protein Isolate
ProteinWhey filtered to 90% or more protein by weight, with most lactose and fat removed.
Typical: 20–30 g
Whey Protein Concentrate
ProteinWhey concentrated by ultrafiltration to 70–80% protein, retaining more lactose, fat, and native bioactive fractions than isolate.
Typical: 25–35 g