Leucine and HMB in resistance training for muscle gains
What it found
In 26 young men doing 12 weeks of resistance training, taking whey protein with HMB led to the same gains in muscle size and strength as taking whey protein with leucine.
The authors say HMB was no better than leucine.
What they found
Studies in people
Muscle mass gains
Fat- and bone-free mass increased by about 2.3 kg in the HMB group and 2.6 kg in the leucine group. The difference between groups was not significant.
Muscle thickness and area
Both groups had about a 5% increase in muscle thickness and similar increases in muscle cross-sectional area. No differences were found between groups.
Strength gains
Squat, bench press, and deadlift strength all increased with training. The increases were similar in both groups, with no significant differences.
Hormone levels
Blood levels of testosterone, cortisol, growth hormone, and IGF-1 changed with training but showed no differences between the HMB and leucine groups at any phase.
Muscle damage marker
Creatine kinase, a marker of muscle damage, increased after overreaching and recovered during taper. The changes were similar in both groups.
What the authors conclude
“Our results show that HMB is no more effective in stimulating RT-induced hypertrophy and strength gains than leucine.”
Also in their conclusions
- They conclude that HMB added to whey did not result in greater increases in any measure of muscle mass, strength, or hormonal concentration compared to leucine added to whey.
- They state that their results show HMB is no more effective in stimulating resistance training-induced hypertrophy and strength gains than leucine.
How it was done
Some studies suggested that HMB, a breakdown product of leucine, might build muscle far better than leucine itself. The authors wanted to test this directly by comparing the two added to whey protein.
They randomly assigned 26 resistance-trained men, average age 23, to take either whey protein plus HMB or whey protein plus leucine twice daily for 12 weeks. Both groups did the same three-phase resistance training program. Muscle size and strength were measured before and after.
What it can’t tell you
- This study was in young men only, so the results may not apply to women, older adults, or other groups.
- The study did not include a non-supplemented control group, so it cannot show what would have happened with training alone.
- The supplementation protocol differed slightly from what is often recommended for HMB, so the findings might not apply to other dosing schedules.
Who paid
- Authors work at
- McMaster University, CANADA; Federal University of Santa Catarina, BRAZIL
The paper
- Title
- Equivalent Hypertrophy and Strength Gains in β-Hydroxy-β-Methylbutyrate- or Leucine-supplemented Men
- Type
- Randomised controlled trial
- Evidence
- Studies in people
- Summarised from
- Full text
- Cite
- Jakubowski JS, Wong EPT, Nunes EA, et al (2019). Equivalent Hypertrophy and Strength Gains in β-Hydroxy-β-Methylbutyrate- or Leucine-supplemented Men. Medicine and science in sports and exercise. doi:10.1249/MSS.0000000000001752Free full textPubMed 30113522DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error