HMB (β-hydroxy-β-methylbutyrate) is a breakdown product of the amino acid leucine (known for its effect on stimulation muscle protein synthesis). HMB has been used as a supplement for the last two decades. It got an upswing after a study (1) found it to increase lean body mass by almost 7 kg after 12 weeks of supplementation. But what about the rest of the research? Let’s look into it.
Mixed Results
Other studies have assessed HMB supplementation effects on strength and body composition and the results are inconclusive. Some studies report small gains in strength and/or body composition whereas others don’t.
No Effect in Trained Individuals
A recently published meta-analysis (a combination of results of multiple studies) aimed to clarify the effects of HMB supplementation on strength and body composition (2). Participants had at least one year of weight training experience or competed at college or professional level. They trained between 2-7 days a week and received daily supplementation with 3 g HMB. The result was that daily HMB supplement didn’t improve strength or body composition.
Benefits in Untrained and Elderly
Other studies show nearly the same result. HMB supplementation with 3 grams per day was shown to have a small effect for gaining fat-free mass and strength when conducted with resistance training in untrained individuals (3-4).
We really mean small effect: around 0.28% more gain in lean mass per week and 1.4% more strength gains per week. Even though the findings are STATISTICALLY significant (p <0.05), meaning that the findings are probably not based on luck, they are not of practical relevance. This means tha a beginner might gain a couple more % muscle on HMB, but that the benefits probably diminish over time.
In addition to this HMB supplementation, when added to a resistance-training program, prevented muscle loss in older individuals (5-6).
In Summary
Supplementation with 3 g HMB a day failed to show a significant effect on body composition or maximal strength in trained individuals. Supplementation may result in small gains in strength and prevent muscle loss in untrained or older individuals. As a beginner, we would recommend you put your money and energy on your workouts rather than on this insignificant supplement.
Check out our beginner workout program to start focusing on the right things!
Article by Maria Ekblom, licensed physiotherapist and personal trainer.
Sources:
- Wilson J et al. The effects of 12 weeks of beta-hydroxy-beta-methylbutyrate free acid supplementation on muscle mass, strength, and power in resistance-trained individuals: a randomized, double-blind, placebo-controlled study. European Journal of Applied Physiology. 2014;114(6):1217-1227.
- Sanchez-Martinez J. Effects of beta-hydroxy-beta-methylbutyrate supplementation on strength and body composition in trained and competitive athletes: A meta-analysis of randomized controlled trials. Journal of Science and Medicine in Sport. 2017;.
- Nissen S. Effect of dietary supplements on lean mass and strength gains with resistance exercise: a meta-analysis. Scandinavian Journal of Medicine and Science in Sports. 2003;13(4):272-272.
- Wu H et al. Effect of beta-hydroxy-beta-methylbutyrate supplementation on muscle loss in older adults: A systematic review and meta-analysis. Archives of Gerontology and Geriatrics. 2015;61(2):168-175.
- Rowlands D. Effects of β-Hydroxy-β-Methylbutyrate Supplementation During Resistance Training on Strength, Body Composition, and Muscle Damage in Trained and Untrained Young Men: A Meta-Analysis. Journal of Strength and Conditioning Research. 2009;23(3):836-846.
- Holeček M. Beta-hydroxy-beta-methylbutyrate supplementation and skeletal muscle in healthy and muscle-wasting conditions. Journal of Cachexia, Sarcopenia and Muscle. 2017;8(4):529-541.
