What is HMB and Are There Benefits for Bodybuilding?

Most of us will recognise the product ‘HMB’ which is available from a number of popular sport supplement suppliers. Although how many of us actually know what it is or what it actually does?

HMB supplements

Also known in its scientific form as ß-Hydroxy ß-methylbutyrate, HMB is a metabolite of the essential amino acid leucine. The product claims to increase lean mass gains, speed recovery and support muscle repair – similar to creatine. Although the mechanism of HMB is not fully understood, research would suggest the key physical benefits are brought about by a reduction in muscle proteolysis (protein degradation) which may occur during intense exercise.

Primarily aimed at bodybuilders and strength/power athletes, the product became a popular ergogenic aid in the mid nineties. Many suppliers saw an opportunity for this product to sell, and so promoted the product assuring overwhelming benefits for the entire population. However, as some of us have found out the hard way – by getting ripped off, suppliers often promote these ‘research proven’ products with a one-sided scientific approach.

Prompting its popularity, Nissen et al, (1996) found significant results suggesting that 3g of HMB per day can decrease the exercise-induced rise in muscle proteolysis. This resulted in increased strength and an increased deposition of free fat mass in untrained individuals. Body composition analysis showed that 1-1.8kg of fat was lost and total strength was increased by 13 and 18.4% respectively over the three week period. Doses of HMB above 3g per day were found to have no further effects.

Although some studies have supported these enhancing effects in young untrained individuals, more significantly the response of resistance/aerobic/anaerobic trained individuals is less clear. The vast majority of studies show no evidence of increased muscle gains, increased strength or reduced body fat in trained individuals (Slater & Jenkins, 2000, Slater et al, 2001, O’Connor & Crowe, 2003, Hung et al, 2010). Current authors believe these conflicting results could be attributed to the variability in humans, inadequate sample sizes, short duration experiments, cases of overtraining and the different testing conditions. There is little research relating to trained participants that may be encouraging; however there is a need for longer more tightly controlled studies involving a range of groups (Wilson et al, 2008).

HMB is a perfectly safe supplement; it is often used in medical practice to treat patients with muscle wasting conditions to reduce muscle proteolysis. Research has suggested that it can reduce systolic blood pressure and reduce total/low density lipoprotein (LDL) cholesterol levels, with no adverse effects on haematology or hepatic or renal function.

In my opinion, HMB may serve a purpose for individuals considering weight training, although other supplements such as whey protein seem a more suitable option for beginners. For competitive athletes and bodybuilders, the product may be worth a try; however, I would look to focus more specifically on products which provide more evidence of effectiveness.


  • Hung, W., Lui, T., Chen, C., & Chang, C.K. (2010). Effect of ß-hydroxy-ß-methylbutyrate Supplementation during Energy Restriction in Female Judo Athletes. Journal of Exercise Science and Fitness, 8, 50-53.
  • Nissen, S.L. et al, (1996). Effect of Leucine Metabolite ß-Hydroxy ß-methylbutyrate on muscle metabolism during resistance-exercise training. Journal of Applied Physiology, 81, 2095-2104.
  • Nissen, S.L. & Sharp, R.L. (2003). Effect of dietary supplements on lean mass and strength gains with resistance exercise: a meta-analysis. Journal of Applied Physiology, 94, 651-659.
  • O’Connor, D.M., & Crowe, M.J. (2003). Effects of ß-hydroxy-ß-methylbutyrate and creatine monohydrate supplementation on the aerobic and anaerobic capacity of highly trained athletes. Journal of Sports Medicine and Physical Fitness, 43, 64-68.
  • O’Connor, D.M. & Crowe, M.J. (2007). Effect of six weeks of ß-hydroxy-ß-methylbutyrate (HMB) and HMB/Creatine Supplementation on Strength, Power and Anthropometry of Highly Trained Athletes. Journal of Strength and Conditioning Research, 21 (2), 419-423.
  • Slater, G.J., & Jenkins, D. (2000). ß-Hydroxy ß-Methylbutyrate (HMB) Supplementation and the Promotion of Muscle Growth and Strength. Sports Medicine, 30 (2), 105-116.
  • Slater, G.D., et al, (2001). ß-Hydroxy-ß-methylbutyrate (HMB) supplementation does not affect changes in strength or body composition during resistance training in trained men. International Journal of Sports Nutrition and Exercise, 11, 384-396.
  • Smith, J.H., Wyke, S.M., & Tisdale, M.J. (2004). Mechanism of the Attenuation of Proteolysis-Induced Factor Stimulated Protein Degradation in Muscle by ß-Hydroxy ß-methylbutyrate. Cancer Research, 64, 8731-8735.
  • Wilson, G.J., Wilson, J.M., & Manninen, A.H. (2008). Effects of ß-hydroxy-ß-methylbutyrate (HMB) on exercise performance and body composition across varying levels of age, sex, and training experience: A review. Nutrition & Metabolism, 5, 1-17.

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