Beta Hydroxy Beta Methylbutyrate (HMB) - The Unsung Hero?

What exactly is HMB?

HMB is a metabolite of the amino-acid leucine. Leucine is an essential amino-acid, but since HMB is derived from leucine it is not itself deemed to be an essential amino-acid. Despite this, the potential benefit of HMB as a metabolite or sport supplement should not be underestimated. Leucine and HMB have both been seen to reduce muscle breakdown (catabolism) both during and after training, potentially increasing training capacity, muscle mass and strength. Leucine is found mainly in breast milk, citrus fruits and catfish, and as mentioned earlier, it is produced endogenously (within the body) from leucine (Kreider, Wilborb, Campbell, Almada, Collins, Cooke et al. 2010).

How does it work?

HMB’s exact mechanism of action is not fully understood, but it is clear that it can help to reduce muscle damage and promote muscle repair! It is thought that HMB acts on the MAPK and PI3K pathways, whilst promoting the expression of Insulin like growth factor- 1 mRNA (IGF-1), a protein proven to aid growth and muscle development. This leads to an increase in myoblast release, a cell used in the repair and growth of muscle. Studies have seen a reduction in creatine phosphokinase levels, a substance produced during muscle breakdown, indicating a reduced level of catabolsim. Alongside this, lactate dehydrogenase (enzyme responsible for the formation of lactic acid) production is decreased, potentially delaying the onset of fatigue and reducing post exercise muscle soreness (Llewellyn, 2009).

Unfair controversy surrounding HMB

As reported by Llewellyn, (2009), HMB was seen (quite unfairly too) as a bit of a letdown in the bodybuilding world. This stemmed from a rash statement by ex EAS supplements owner Bill Phillips, who compared HMB to a very potent anabolic steroid setting highly unrealistic expectations! Naturally, HMB failed to deliver the expected results; this is because HMB delivers its effects more subtly and over a longer duration. Steroids deliver rapid gains in strength and mass, but expose the consumer to nasty, undesirable and potentially dangerous side-effects.......not to mention they’re illegal. HMB (especially when consumed alongside creatine) could promote muscle growth, reduce fatigue and potentially increase strength, without the stigma, undesirable side-effects and controversy that surrounds steroids. HMB should not be sneered at because of an unreasonable and completely unrealistic expectation set by one person; it is widely regarded as a useful performance enhancing supplement, especially in lesser developed individuals and those that are new to training. HMB has demonstrated the ability to increase muscle mass by approximately 0.5- 1kg by 3-6 weeks of training (Llewellyn, 2009; Greenwood, Kalman, & Antonio, 2008).

How and when to use HMB

HMB is best consumed immediately before or during training at a dosage of 1.5- 3 grams per day. Best results were seen when consumed alongside creatine, meaning the two supplements exert a cumulative effect making for a useful supplement stack/bundle (Jowko, Ostaszewski, Jank, Sacharuk, Zieniewicz, et al. 2001). Ideally HMB would be consumed within 30mins prior to, or during your training session, alongside a creatine monohydrate (taken approx mid-morning for example) and a whey protein supplement (within 30mins after training). HMB has been seen to be most effective in relatively untrained individuals and the elderly, meaning it offers itself to a broad market. The extent of its effects amongst elite/professional athletes or high level amateurs are still not clear, but it is anticipated that this supplement would be a useful, risk free addition to anybodies training, diet and supplement regimen (Llewellyn, 2009; Kreider, Wilborb, Campbell, Almada, Collins, Cooke et al. 2010).


Greenwood, M., Kalman, D, S. & Antonio, J. (2008). Nutritional Supplements in Sports and Exercise. Conjugated Linoleic Acid. New Jersey: Humana Press.
Jowko E, Ostaszewski P, Jank M, Sacharuk J, Zieniewicz A, Wilczak J, Nissen S, (2001). Creatine and beta-hydroxy-beta-methylbutyrate (HMB) additively increase lean body mass and muscle strength during a weight-training program. Nutrition, 17(7-8):558-66
Kreider, R, B., Wilborb, C, D., Campbell, B., Almada, A, L., Collins, R., Cooke, M, (2010). ISSN exercise & Sport Nutrition Review: Research & Recommendations. Journal of the international society of sports nutrition. 7: 1550-2783.

Llewellyn, W, (2009). Sport Supplement Reference Guide. Conjugated-Linoleic Acid (CLA). Military trail: Molecular Nutrition LLC of Jupiter.

About the Author

Job Role Qualified Dietitian and Sports Nutritionist Qualifications BSc (Hons) Sports Science | BSc (Hons) Dietetics Tom has always participated in sport both recreationally and competitively which led to an unquenchable thirst for information on anything health, nutrition and fitness. After leaving school Tom went on to play for a football academy during which time he studied Sport and Exercise Science. From here he went on to study a BSc (Hons) Sport Science at UEA followed by his second BSc (Hons) degree, this time at the University of Hertfordshire studying Dietetics. Tom has worked in the fitness, educational and clinical nutrition industry starting out at David Lloyd Health and Leisure Clubs. He then went on to work as a Dietitian (RD) in the NHS, during which time he conducted clinics for healthy eating, weight loss and weight gain, as well as specialised consultations on Diabetes, IBS and Coeliac disease to name a few. He has vast amounts of experience at devising diet plans and supplement regimens, as well as working in the community with schools and competitive athletes. As Head Nutritionist and Supplement expert at Discount Supplements Tom is here to provide current and evidence based health and nutrition information to help you reach your health and fitness goals!
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