Research

Hormonal

Oral consumption of 2.42 g of free-acid β-hydroxy-β-methylbutyrate (HMB) acutely stimulates muscle protein synthesis (MPS) to a similar extent as 3.42 g of leucine, while uniquely reducing muscle protein breakdown (MPB) by 57% in an insulin-independent manner.

Take 2.42 grams of free-acid HMB on an empty stomach to acutely boost muscle protein synthesis and reduce muscle breakdown. This works without spiking insulin, making it a distinct anabolic signal compared to leucine or protein meals.

GoodSupportsHIGH confidence
Orally consumed 3.42 g free-acid (FA-HMB) HMB (providing 2.42 g of pure HMB)... stimulated muscle protein synthesis (MPS; HMB +70% vs. Leu +110%). HMB consumption also attenuated muscle protein breakdown (MPB; −57%) in an insulin-independent manner.
Daniel J. Wilkinson et al. · The Journal of Physiology · 2013

Why this rating

High-quality human tracer study with rigorous controls, though limited to healthy young men and acute timeframes.

Source

Effects of leucine and its metabolite β‐hydroxy‐β‐methylbutyrate on human skeletal muscle protein metabolism

Daniel J. Wilkinson et al. · The Journal of Physiology · 2013

DOI 10.1113/jphysiol.2013.253203

rct · n=15Cited 474×
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DOI resolved against Crossref · corpus check 2026-06-10

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