What is HMB and what are its benefits?

What is HMB and what are its benefits?

We could say that HMB is one of the supplements that has caused more expectation and controversy in the last few years

Who is to blame? There are certain studies that show radical changes in terms of body composition such as: gaining 7kg of “muscle tissue” while losing 5kg of fat. Other studies show how HMB can preserve the muscle mass both for athletes and those who cannot do exercise (due to an injury, for example). But before diving further into this, let’s explain some basic concepts.

What is HMB?

HMB is ß-hydroxy-ß methylbutyrate, a natural compound produced during the metabolization of l-leucine (one of the branched chain amino acids or BCAA’s).

Dr. Steven Nissen was the one who discovered the important role of HMB for the protein synthesis. This means that it has the ability to increase the strength, reduce the muscle breakdown and shorten the recovery.

The original patent for HMB as a food supplement was given to Dr. Nissen. Since then, HMB supplements have become very popular among bodybuilders in order to support muscle growth with excellent results. However, in spite of its popularity, most people know very little about how does HMB work and what is its role on the body.

HMB is naturally produced in our body during the leucine metabolism, which belongs to the BCAA’s

Why take HMB?

HMB will come into play when our cells are damaged because its main task is to reduce the damage to the muscle tissue. That is why is necessary to stimulate our body through the workout, only then will this supplement make sense within our training routine.

Therefore, we are going to be talking about a recovery and anti-catabolic supplement. Consequently, this would eventually lead to anabolism.

The body is always trying to regulate itself in order to reach the homeostasis. That is why it will perform the necessary functions in order to adapt to the stimulus. If we are capable of becoming stronger each session, it will be only because our body will repair the connective tissues and muscle cells. In this way, we will be able to face the next workout session successfully.

The benefits of HMB

1. It stimulates the protein synthesis

It increases the muscle mass while avoiding the catabolism: it stimulates the protein synthesis to improve the muscle growth. We will not gain any muscle when the protein synthesis is equal to the protein breakdown.

This is relevant for the maintenance / strength gain ratio. HMB helps to increase the muscle protein in two ways:

  • HMB lowers the protein breakdown at a molecular level caused by intense workouts. It inhibits the proteolysis, the natural process that breaks down the muscle tissue after an intense exercise, like weightlifting. This occurs through the ubiquitin proteolytic proteasome pathway, because the proteolytic enzyme breaks down the muscle protein.
  • HMB is a leucine metabolite, which belongs to the BCAA's. It stimulates the protein synthesis through the mTOR/p70S6k pathway.

After three weeks of HMB supplementation and weightlifting, untrained subjects were capable of increasing their lean muscle mass in a 300% (Nissen et al, 1996a). These results have been supported by other researchers as well (Gallagher et al, 2000; Jowko, 2001).

HMB and muscle mass

Enhancing the synthesis and reducing the break down results in more strength and a shorter recovery

2. It helps to lose body fat

In the previous studies, they also observed that the amount of fat loss was significantly higher in those who took HMB supplementation. Moreover, HMB was also effective in lowering the bad cholesterol or LDL in those who had a high blood cholesterol (Nissen, 2000).

3. It shortens the muscle recovery processes

HMB reduces the muscle damage caused by exercise, which shortens the recovery time between training days. Everyone knows how the day after an intense workout session feels like.

However, HMB helps to reduce the muscle damage and the protein breakdown as much as possible during an intense workout.

A lower protein breakdown means more muscle cell stability and less damage to the membrane. This can be measured with muscle damage markers such as creatine phosphokinase (CPK) in the bloodstream.

4. It increases the strength

Strength gains are enhanced with HMB. A meta-analysis about endurance training and HMB supplementation resulted in a strength increase. The studies recorded this improvements in trained and untrained men, women, young and old people.

The general results were clear, although the effect varies depending on the intensity of the workout and the chosen group (Nissen and Sharp, J. Applied Physiol. 94:651-659, 2003).

HMB improves the performance

HMB significantly increases the strength gains when it is combined with an endurance training.

5. It increases the VO2 max and the resistance

HMB improves the aerobic capacity in endurance athletes (runners, cyclists and triathletes).

ß-hydroxy-ß methylbutyrate increases the oxygen consumption (VO2 Max) and improves the respiratory compensation point (RCP). It seems that HMB can lower the metabolic acidosis and support athletes in high intensity workouts for a long period of time.

The research also shows how HMB delays the onset of blood lactate accumulation (OBLA).

Side effects of HMB

HMB is a metabolic product, it is water soluble and an excess can be excreted through the urine. Its safety has been reviewed in several studies that showed how taking between 3 and 6g/day for several months did not trigger any side effects.

Recommended daily dose and use

The recommended daily dose of HMB is 3g daily for those who have an average size. The conversion of leucine to HMB is extremely inefficient. You would need to take 60g of leucine to obtain HMB. Consequently, it is extremely difficult to get 3g of HMB only through the diet.

That is why it is advisable to take HMB supplements

To “customize” the dose (Strength and Muscle Building: 2000: Gallagher), the research has proven that 17-38mg per kg of body weight daily is an optimal amount.

You need to distribute the daily dose in two or three equal servings and take them throughout the day:

  • After waking up
  • For the post-workout
  • 4 hours after training
We suggest taking one of the daily HMB serving one hour before training to lower the muscle damage. If you cannot take HMB before doing exercise, then take a dose immediately after training.

Combine HMB with other supplements

Take HMB with a balanced diet that provides a daily protein supply (around a gram per kilo of body weight). This is specially advised if you follow and active lifestyle.

If your diet is not balanced or the protein supply is low, then HMB has to be combined with vitamins, minerals and protein.

The research shows how combining HMB with creatine provides better results than taking HMB or creatine alone. Combining these two supplements enhances the performance of strength athletes

Questions about HMB

  • How does HMB work?

    HMB reduces the muscle catabolism by:

    • Decreasing the tissue breakdown caused by physical exercise. There is a inhibition of the ubiquitin proteolytic proteasome pathway
    • Increasing the protein synthesis by stimulating the mTOR pathway and reducing the blood corticosterone concentrations (said hormone increases during periods of stress and anxiety, like training)
  • What are the benefits of HMB for athletes?

    As trained persons, the main benefits that we will get from HMB will be:

    • Anabolic
    • Anti-catabolic

    In turn, this will:

    • Increase the muscle strength
    • Improve the performance: increasing the resistance and the VO2 MAX
    • Prevent overtraining
    • Relieve the muscle soreness
    • Shorten the recovery processes
    • Reduce the fat percentage

    Moreover, when it comes to improving our health, it will lower the risk of suffering a heart attack:

    • Protecting the cell membrane (post-workout protein breakdown)
    • Lower the blood pressure
  • How much and how many servings of HMB daily?

    • The studies that have been conducted have concluded that a dose of 3g of HMB daily will provide all its benefits.
    • Distribute this dose throughout the day, mainly before and after training, as well as after waking up and before going to sleep.
  • How long does it take to experience its effects?

    • The main effects of HMB in terms of muscle mass and strength will depend on the person. But, in general, trained subjects who follow a healthy lifestyle will experience them between 2-4 weeks.
  • Can we combine HMB with other supplements?

    • Yes, you can combine it with: creatine, protein, glutamine. You can even stop using BCAA’s, since HMB is a leucine metabolite 20 times more powerful that leucine itself.
  • Can women take HMB?

    • Yes, since it can even increase their strength and help them achieve a better physical composition.
  • Who can benefit from taking HMB?

    • HMB is specially meant for those who want to prevent the muscle breakdown. This is useful during periods of caloric restriction or cutting phase. Also, those who want to improve the post-workout recovery processes, especially if they perform intense activities regularly.
    • Don’t forget that HMB will be more effective when the training method is efficient. Following a good diet and creating an anabolic environment will be necessary for the protein synthesis to take place.

HMB in two formats

First of all, we have HMB-Ca (calcium salt) and HMB-FA (acid free form).

For those who don’t know, HMB is a leucine metabolite. In other words, leucine is a precursor form of HMB. However, only a 5% of the leucine becomes HMB4, which is why we would need to take 60g of leucine to produce 3g of HMB. That’s why it is interesting to pick the most bioavailable supplement.

Even though we may think that leucine may have the same hormone mechanism, that is not the case. The truth is that leucine helps to preserve the muscle mass since it stimulates the muscle protein synthesis. Unlike HMB, leucine does not increase the IGF-1 levels (insulin growth factor)5.

IGF-1 activates the chain reactions connected to muscle growth and development. Moreover, it inhibits the pathways that cause protein breakdown (through FOXO), which would explain its benefits for the muscles.

Hormone effects of HMB

HMB and hypertrophy

As we can see in this image7, IGF-1 improves the muscle growth and inhibits the loss produced by drugs or injuries.

HMB and IGF1

Area under the IGF-1 curve. HMB has much higher levels of IFG-1 than the placebo.

Studies on HMB

The first studies on HMB were conducted on 1996. They picked a group of people who were given 3 amounts of HMB: 0, 1.5 and 3 grams of HMB. Their purpose was to see what effect did they have in terms of physical composition.

They noticed that there was a negative relation between HMB and the protein breakdown. This means that, the higher the HMB dose, the lower the protein breakdown was. This discovery increased the interested in HMB and its effects on the physical composition. In the end, it obtained modest results against the placebo 9 in which the participants gained 1.4% of muscle mass and lost 1.1% fat.

HMB and Muscle composition

When we reviewed the studies about HMB, we found out that:

HMB bibliography

As we can see, HMB can support those who can lose muscle mass more easily. However, it is harder in healthy subjects to achieve hypertrophy. As we previously discussed, these studies are based on HMB-Ca, but not on acid free HMB (HMB).

Quite recently, there has been a study on the effects of HMB on a metabolic level. To do this, they chose healthy subjects with a relatively low fat percentage (13%) and 7 years of training at least. As expected, the plasma HMB levels were quite good when compared to other studies that used HMB.

Comparison between HMB and placebo

Pre-workout HMB levels(PRE), immediately after training(IP) and 30 minutes post-workout (30P)

These were the results in terms of the testosterone level and the growth hormone:

HMB effects on testosterone and growth hormone

The testosterone levels increased in both groups just after training. However, after 30 minutes, the levels drop to the pre-workout levels. This could explain why increasing the post-workout testosterone levels does not affect the muscle mass. Nevertheless, there were higher levels of the growth hormone (GH) in the group who took HMB.

Summary about HMB

There is plenty of information that proves how beta-hydroxy-beta-methylbutyrate (HMB) can:
  • Enhance the strength
  • Increase the muscle mass
  • Improve the weight loss

Moreover, it can even improve our health overall. HMB does not produce side effects and it is available in many stores. All in all, it has many benefits for bodybuilders, athletes, as well as those who want to stay in shape and/or lose weight.

Do you want HMB supplements? Click in HSN


  1. 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.Wilson JM1, Lowery RP, Joy JM, Andersen JC, Wilson SM, Stout JR, Duncan N, Fuller JC, Baier SM, Naimo MA, Rathmacher J.
  2. β-Hydroxy-β-methylbutyrate free acid reduces markers of exercise-induced muscle damage and improves recovery in resistance-trained men.Wilson JM, Fitschen PJ, Campbell B, Wilson GJ, Zanchi N, Taylor L, Wilborn C, Kalman DS, Stout JR, Hoffman JR, Ziegenfuss TN, Lopez HL, Kreider RB, Smith-Ryan AE, & Antonio J
  3. Effect of calcium β-hydroxy-β-methylbutyrate (CaHMB) with and without resistance training in men and women 65+yrs: a randomized, double-blind pilot trial.Stout JR1, Smith-Ryan AE, Fukuda DH, Kendall KL, Moon JR, Hoffman JR, Wilson JM, Oliver JS, Mustad VA.
  4. β-Hydroxy-β-methylbutyrate reduces myonuclear apoptosis during recovery from hind limb suspension-induced muscle fiber atrophy in aged rats.Hao Y1, Jackson JR, Wang Y, Edens N, Pereira SL, Alway SE.
  5. Effects of beta-hydroxy-beta-methylbutyrate (HMB) on exercise performance and body composition across varying levels of age, sex, and training experience: A review.Wilson GJ1, Wilson JM, Manninen AH.
  6. Tissue-specific effects of chronic dietary leucine and norleucine supplementation on protein synthesis in rats.Lynch CJ1, Hutson SM, Patson BJ, Vaval A, Vary TC.
  7. Balancing muscle hypertrophy and atrophy.Eric P Hoffman & Gustavo A Nader
  8. Effect of leucine metabolite beta-hydroxy-beta-methylbutyrate on muscle metabolism during resistance-exercise training.Nissen S
  9. Effects of beta-hydroxy-beta-methylbutyrate (HMB) on exercise performance and body composition across varying levels of age, sex, and training experience: A review. Gabriel J Wilson1*, Jacob M Wilson2 and Anssi H Manninen3
  10. Kinetics of human growth hormone during submaximal exercise.Lassarre C, Girard F, Durand J, Raynaud J.

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HMB Review

Reduces Creatine Kinease - 100%

Muscle Recovery - 100%

Reduces the fat percentage - 94%

Strength gains - 93%

Preserves the muscle mass during cutting phase - 100%

Muscle gains - 86%

Physical performance - 90%


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About Sergio Espinar
Sergio Espinar
Sergio Espinar is a sport nutritionist, specialized in fat loss and health in women. Coach, professor and speaker in the HSN Fitness School.
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