ISSA, International Sports Sciences Association, Certified Personal Trainer, ISSAonline, Nutrition, Is an HMB Supplement for Exercise Effective? Is it Safe?

Is an HMB Supplement for Exercise Effective? Is it Safe?

Reading Time: 6 minutes 28 seconds


Date: 2021-01-22T00:00:00-05:00

As a personal trainer, you field a lot of varied questions from clients, friends, and family. Are you prepared to answer them? While your scope of practice limits recommendation of supplements, it is important to be able to provide clients with information.

HMB supplementation is not new. It has flown under the radar for years, mostly popular with serious bodybuilders. Your clients interested in changing their body mass and building muscle may read about it and want to know more.

HMB is a protein-related supplement that is considered safe and effective for some purposes. It may help improve body composition, muscle recovery, and muscle mass.

What is HMB?

HMB is beta-hydroxy beta-methylbutyrate. It is a metabolite of the amino acid leucine, which means that when you consume leucine, it is converted to HMB, among other molecules. Athletes, especially bodybuilders, have long used HMB to promote muscle growth and to improve performance.

Many people also use leucine, as part of a branched chain amino acid (BCAA) supplement, to enhance performance. It may be that the metabolite HMB is responsible for the positive effects of BCAA supplements.

Leucine, possibly through HMB, promotes muscle hypertrophy and strength. It reduces muscle breakdown and increases muscle growth. If HMB is behind the benefits offered by leucine and BCAA supplements, it may make sense to go straight to the source and supplement with HMB.

What Are the Benefits of HMB Supplementation?

The research on HMB supplementation is mixed but many studies provide evidence for benefits. Studies range from using HMB in trained athletes, untrained non-athletes, older adults, and cancer patients. There is some variation between populations, but in general HMB seems to have several benefits.

HMB Increases Lean Body Mass

When combined with regular strength training, HMB supplements increase fat-free body mass. In other words, it promotes a shift in body composition from more fat and less muscle to less body fat and more lean muscle mass. Studies show the effects are similar in men and women. (1)

While many studies show that HMB supplementation increases lean body mass, some see no effect in trained athletes. (2) The results here are mixed, but the evidence is clear that HMB does support lean body composition in people with little or no experience weightlifting. Your new clients may benefit more from an HMB supplement than your experienced lifters.

An HMB Supplement for Exercise Enhances Recovery

HMB may affect lean body mass through its mechanism of action: reducing proteolysis, the breakdown of proteins and muscle tissue, and increasing protein synthesis. Not only do these actions promote muscle growth and strength gains, but they also promote recovery.

The International Society of Sports Nutrition takes the position that HMB supplementation enhances post-workout recovery. (3) HMB reduces muscle damage, promoting quicker recovery. It also seems to decrease the DOMS (delayed-onset muscle soreness) that many people experience after a workout. HMB seems to be effective for recovery in both trained athletes and untrained people.

Learn more about the mystery that is DOMS and why some people seem to suffer more than others post-workout.

HMB Promotes Muscle Hypertrophy, Strength, and Power

While the evidence is mixed in trained athletes, the general consensus is that a supplement of HMB does improve strength, growth, and power in muscles. Untrained people see the greatest effects, but lifters and bodybuilders also get the benefits, according to most studies.

Because the impact is greater in untrained individuals, HMB may be particularly useful for people who are sedentary or have health problems that lead to muscle wasting. As we age, we tend to lose muscle mass naturally, so HMB may help older adults hold onto more muscle tissue. Patients with illnesses that cause muscle wasting, like advanced cancer, may also benefit.

What seems to be important in getting this effect is the combination of HMB with strength training and resistance exercise. Older adults, obese clients, or people with muscle wasting may benefit from physician-directed, appropriate training along with a supplement.

There's a lot of information out there about muscle gain and improving muscle strength. The truth is that muscle building isn't that complicated. Give your clients this guide to building muscle to answer all their questions.

HMB May Support Weight Loss and Maintenance

Because HMB helps improve body composition, reducing fat and increasing muscle mass, it could be a useful tool for weight loss programs. Most studies focus on athletic performance and muscle building, but the benefits of HMB lead directly to a healthier weight and body composition.

Essential to using this supplement to aid a healthy weight is exercise. Most of the benefits of HMB supplementation are found in people engaging in training sessions, specifically strength and resistance training. Make sure your clients understand that HMB cannot help them lose weight if they are sedentary.

ISSA, International Sports Sciences Association, Certified Personal Trainer, ISSAonline, Nutrition, Is an HMB Supplement for Exercise Effective? Is it Safe?, Creatine

What About HMB with Creatine?

Your clients looking into supplements will find products that combine these two substances. Creatine is an amino acid that most people get from eating meat. It is not an essential amino acid because the body can synthesize it from glycine and arginine.

Most creatine in the body is converted to phosphocreatine and stored in muscle tissue. There it helps produce more ATP, the energy currency of cells. The more ATP you have, the more energy you have for exercise, which is a common reason why people supplement creatine.

Research evidence suggests that creatine supplements are especially useful for bursts of energy in sports like weightlifting and sprinting. (4) It may also boost muscle mass and slow protein breakdown.

The evidence for increased benefits by combining HMB and creatine is mixed. A review of multiple studies found that the combination improves sports performance and body composition but not recovery. (5)

Another study found no performance improvements in athletes when using the combination as compared to the use of creatine alone. (6) Creatine and the creatine/HMB combination are generally considered safe.

Is an HMB Supplement for Exercise Safe?

Studies have found that there are no adverse effects when supplementing with 3-6 grams of HMB per day. This includes in elderly participants. Animal studies showed no adverse effects even with very large amounts of HMB. (1)

These studies even show that there are potential benefits beyond any potential for muscle growth (1):

  • Improved mood

  • Decreased total cholesterol

  • Decreased LDL cholesterol in people with high levels

  • Decreased blood pressure

  • Improved wound healing and immune system function

How to Use HMB Supplements

While studies have looked at safety in doses up to 6 grams, most results suggest no or minimal benefits past 3 grams per day. Even studies of just 1.5 grams of supplement shows there are benefits at this level. Three grams is likely the ideal amount for most people.

The International Society of Sports Nutrition position paper recommends that HMB is most effective when used within 60 minutes of a training session, ideally prior to the exercise. The paper also suggests that you'll get the most benefits from HMB when taken daily for two weeks prior to an athletic event.3

Should You Recommend an HMB Supplement for your Clients?

Your scope of practice as a personal trainer, or even as a nutrition coach, is limited. You generally cannot recommend supplements or amounts to clients. What you can and should do is provide clients with information and suggest they talk to their doctors about what supplements would be safe and appropriate.

This is especially true for clients with health problems. While HMB may be useful for people struggling to maintain muscle tissue due to illness, it is essential that they talk to their doctors first. HMB seems to be safe for everyone, but only an individual's doctor can confirm this.

Having answers to questions is an important part of being a nutrition coach and personal trainer. Clients come to you for information and expertise on fat loss, strength gains, fitness-related nutrition, and more. So be ready to provide it even if you can't actually recommend supplements like HMB.

Interested in nutrition as it relates to fitness? Get the ISSA's Nutritionist course to learn everything you need to launch a career dedicated to helping clients achieve their health and fitness goals.

  • Panton, L.B., Rathmacher, J.A., Baier, S., and Nissen, S. (2000, September). Nutritional Supplementation of the Leucine Metabolite Beta-Hydroxy-Beta-Methylbutyrate (HMB) During Resistance Training. Nutrition. 16(9), 734-9. Retrieved from

  • Wilson, G.J., Wilson, J.M., and Manninen, A.H. (2008). Effects of Beta-Hydroxy-Beta-Methylbutyrate (HMB) on Exercise Performance and Body Composition Across Varying Levels of Age, Sex, and Training Experience: A Review. Nutr. Metab. (Lond.).5(1), doi: 10.1186/1743-7075-5-1. Retrieved from

  • Wilson, J.M., Fitschen, P.J., Campbell, B., Wilson, G.J., Zanchi, N., Taylor, L., Wilborn, C., Kalman, D.S., Stout, J.R., Hoffman, J.R., Ziegenfuss, T.N., Lopez, H.L., Kreider, R.B., Smith-Ryan, A.E., and Antonio, J. (2013, February 2). International Society of Sports Nutrition Position Stand: beta-hydroxy-beta-methylbutyrate (HMB). J. Int. Soc. Sports Nutr.10(6). Retrieved from

  • Mayo Clinic. (2017, October 12). Creatine. Retrieved from:

  • Fernandez-Landa, J., Calleja-Gonzalez, J., Leon-Guereno, P., Caballero-Garcia, A., Cordova, A., and Mielgo-Ayuso, J. (2019, October). Effect of the Combination of Creatine Monohydrate Plus HMB Supplementation on Sports Performance, Body Composition, Markers of Muscle Damage and Hormone Status: A Systematic Review. Nutrients.11(10), 2528. Retrieved from

  • Mangine, G.T., VanDusseldorp, T.A., Hester, G.M., Julian, J.M., and Feito, Y. (2020). The Addition of β-Hydroxy β-Methylbutyrate (HMB) to Creatine Monohydrate Supplementation Does Not Improve Anthropometric and Performance Maintenance Across a Collegiate Rugby Season. J. Int. Soc. of Sports Nutr.17(28). Retrieved from

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