What It Is, Benefits, & More

Hydroxymethylbutyrate (HMB) is a substance found in the body that is a by-product of leucine metabolism. Leucine is one of three essential branched-chain amino acids.

The body produces HMB in small amounts when it metabolizes leucine. Certain foods also contain small amounts of HMB. In the human body, HMB is needed for protein metabolism, insulin activity, and muscle growth.

Research shows that HMB influences protein synthesis by stimulating certain cellular pathways. For this reason, it is commonly used as a supplement by athletes and those looking to improve muscle mass.

There is also evidence that HMB may improve endurance, exercise recovery, and sarcopenia (muscle wasting). HMB is generally regarded as safe to use by most people.

This article will discuss the research behind various uses of HMB. It will also cover side effects, precautions, dosage, interactions, and other important information you should know before using HMB.

Supplement Facts

  • Active ingredient(s): Hydroxymethylbutyrate (HMB)
  • Alternate name(s): HMB, beta-hydroxy-beta-methylbutyrate, b-hydroxy-b-methylbutyrate
  • Legal status: Available online and over the counter in many retail and grocery stores.
  • Suggested dose: Dosage varies. For improvements in muscle mass, manufacturers typically recommend taking 3 grams (g) of HMB daily.
  • Safety considerations: Side effects may be possible, and certain people should avoid using HMB.

Uses of HMB

Supplement use should be individualized and vetted by a healthcare professional, such as a registered dietitian, pharmacist, or healthcare provider. No supplement is intended to treat, cure, or prevent disease. 

HMB is a popular supplement among exercise enthusiasts and is commonly used to enhance muscle strength and endurance. There is some scientific evidence that HMB may improve certain parameters of physical fitness due to its perceived ability to increase protein synthesis and decrease muscle damage.

There is also interest in using HMB in people 65 and older. Research shows that HMB may prevent muscle wasting, a typical part of aging.

Other uses of HMB are not supported by scientific evidence.

The next sections will outline some of the research behind common uses of HMB.

Muscle Strength

Studies have suggested that HMB supplementation may be able to enhance muscle strength and growth (hypertrophy) in a wide range of people, including athletes and older adults.

We’ve learned from research that HMB improves the integrity of muscle cells and reduces the breakdown of proteins, which are vital to muscle health.

According to a meta-analysis, HMB supplementation has been found to increase muscle strength and power output when combined with resistance training, Using HMB may also increase lean body mass.

However, HMB may not be effective for everyone.

A different review found that HMB is most useful for those who partake in intense strength exercises. HMB may also be particularly effective for people who have experienced muscle loss or weakness due to aging or certain health conditions. This may be due to HMB’s ability to suppress proteolysis (protein degradation) and increase protein synthesis.

However, HMB may be less effective in strength-trained athletes who have adapted to their exercises.

It’s important to note, though, that not all studies on HMB have found the supplement to affect muscle strength positively.

Researchers from another review could not find a correlation between HMB supplementation and significant increases in muscle strength. However, the review only looked at studies of adults between 18 and 45 years old.

Regardless, research should continue on HMB and its role in muscle strength.

Muscle Damage

Along with supporting muscle strength, studies have shown that HMB may aid recovery, particularly when it comes to muscle damage. Muscle damage is a common occurrence of various types of exercise.

In one small study, 42 highly trained males were randomized to supplement with either a placebo or HMB. The study took place over 12 weeks, during which time the participants practiced intensive combat sports. At the end of the study, researchers observed a reduced rate of muscle damage in the participants who took HMB, possibly due to a decreased rate of protein decomposition caused by HMB.

A 2022 mini-review concluded that HMB may decrease muscle damage caused by exercise, but it’s unclear exactly how the process works. Whether HMB reduces muscle damage may depend on how much of the supplement you take, when you take it, and for how long.

More research may be needed to draw conclusions on if and how HMB decreases muscle damage and improves overall muscle recovery.

Aerobic Endurance

Some evidence supports the use of HMB for better endurance. Although, research results on this topic are mixed.

According to one review, HMB supplementation has been found to improve endurance (also known as aerobic performance) in multiple studies. But other studies included in the review found no benefits to using HMB for endurance. If HMB does enhance endurance, it may do so by improving how energy is utilized during exercise.

A small study performed on rowers found that HMB was superior to placebo in increasing aerobic capacity. The study took place during 12 weeks of rowing training. Rowers who used HMB were also found to have less fat mass at the end of the study.

HMB may also improve endurance in older adults.

In a study on healthy women over the age of 65, participants received either HMB or a placebo over the course of eight weeks. Throughout the study, the women completed various physical tests, including handgrip strength and endurance. It was concluded that supplementing with HMB significantly improved handgrip endurance compared to a placebo.

Despite these positive results, further research is necessary to strengthen the claims that HMB improves endurance, especially since many studies have shown opposing results.


Aging can come with various changes, including frailty, muscle weakness, and challenges when recovering from illnesses and diseases. Some research suggests that HMB supplementation may improve these and other aspects of aging.

In some studies, HMB has been shown to increase muscle strength in the extremities (arms and legs) of older populations. These improvements in strength may reduce the risk of falls, fractures, and muscle-related disorders.

According to one review, prolonged use of HMB has been associated with decreased rates of age-related muscle loss and improved muscle quality in older adults. HMB may also help prevent severe muscle loss that may occur with bed rest. There is also interest in using HMB to preserve cognitive function and bone health in older adults.

Combining HMB supplementation with resistance training is believed to improve outcomes for older adults even more. However, according to one review, research has yet to prove this theory. There also is not enough research yet on HMB’s potential role in other aspects of aging, like cognitive impairment and limited mobility.

As with other uses of HMB, more research is warranted.

What Are the Side Effects of HMB?

Using supplements like HMB comes with a risk of side effects.

HMB is considered safe for most people, and few side effects have been reported in the literature. In fact, many animal and human studies have reported no side effects or adverse events related to using HMB.

There is some concern that HMB supplementation may lead to a protein imbalance. In theory, such an imbalance may cause other tissues not to get the amino acids they need. However, such effects have not been proven.

Despite its apparent safety profile, HMB may cause side effects in some people. Play it safe and use HMB only as directed, never take more than you should, and work with a healthcare provider to find a proper dosage.


HMB is considered safe for most people to use, but some should take precautions.

At this time, there isn’t strong evidence supporting the use of HMB during pregnancy or breastfeeding. If pregnant or breastfeeding, talk with a healthcare provider before using HMB. It may be best to avoid it altogether.

There is still much to learn about HMB, particularly its safety and whether certain people should avoid using it. It’s recommended to talk with a healthcare provider before using HMB if you have any medical conditions or take prescription medications. A healthcare provider can help you determine if HMB is safe for you.

Dosage: How Much HMB Should I Take?

Always speak with a healthcare provider before taking a supplement to ensure that the supplement and dosage are appropriate for your individual needs. 

HMB dosage can vary and may depend on your age, reason for use, and other factors.

Studies have typically used doses ranging from 1 gram (g) per day to 3 g per day. Additionally, some studies have safely used doses of up to 6 g of HMB per day. These doses have been used in various studies, including those on physical performance, muscle mass, and muscle loss.

For muscle mass and function, many manufacturers recommend a dose of 3 g of HMB per day.

There is inconsistent information regarding how long you should use HMB. You may need to use HMB for at least two weeks to see potential effects. Although, participants in some studies have used HMB for as long as 24 weeks or more.

It’s best to follow dosage directions as written on the packaging of the HMB supplement you choose or as recommended by a healthcare provider.

What Happens If I Take Too Much HMB?

You may be more likely to experience side effects if you take too much HMB. However, no reports of toxicity, overdose, or other adverse events linked to using too much HMB have been recorded.

Regardless, it’s important to use HMB only as directed. Just because side effects and adverse events are minimal for HMB does not mean they’re not possible.

It’s vital that you always follow HMB dosage guidelines and never take more than you should.


Some supplements interact negatively with certain medications, supplements, herbs, or foods. This may lead to a supplement or medication not working properly.

There are no documented interactions for HMB. However, interactions may still exist. More research is needed on HMB to determine if it interacts with anything.

To be safe, talk with a healthcare provider before starting HMB if you use other supplements or herbs or take any medications.

It is vital that you carefully read the ingredients list and nutrition facts panel of a supplement to know which ingredients and how much of each ingredient is included. Always review supplement labels with a healthcare provider to discuss any potential interactions with foods, other supplements, and medications. 

How to Store HMB

Store HMB supplements in a cool, dry place and keep them directly out of direct sunlight. It’s important that supplements never get overly hot or cold. You do not need to store HMB in the refrigerator.

Store HMB supplements in their original packaging, making sure the container is air-tight. Keep HMB out of the reach of pets and small children, who may accidentally ingest too much of it. And discard HMB once it reaches its expiration date, which is typically listed on the bottle or packaging. Supplements may lose their potency once they expire.

Similar Supplements

Other supplements may work similarly to HMB. These include:

  • Creatine: Creatine is another substance produced naturally by your body that is thought to benefit muscle strength and growth. A scoping review found that creatine may increase muscle mass, muscle strength, and athletic performance in healthy young populations. The review also mentioned that evidence supporting creatine’s use in older adults is mixed.
  • Branched-chain amino acids: Some people use branched-chain amino acid (BCAA) supplements to improve physical performance. However, research surrounding BCAAs (leucine, valine, and isoleucine) is unclear. One review concluded that BCAAs may have an insignificant effect on performance and body composition but may help with muscle recovery and soreness after exercise.
  • Whey: Whey is a type of protein found in milk. It’s commonly used as a supplement by athletes and others to increase protein intake. There is some evidence that whey protein supplements increase protein synthesis and muscle performance in people over age 65.
  • Casein: Along with whey, casein is one of two proteins found in milk. It has been extensively researched and found to have a potential role in muscle health.
  • Beta-alanine: Beta-alanine is an amino acid made by the liver that plays many roles in the body. Beta-alanine is known to increase levels of carnosine, a substance essential to muscle health. Research shows that beta-alanine may be best suited for short bouts of exercise.

It may not be safe to use more than one supplement at a time for the same purpose. Talk with a healthcare provider about which supplement is best for you.

Frequently Asked Questions

  • Is HMB safe?

    Yes, HMB is generally considered safe for most people to use. Very few side effects have been associated with the use of HMB.

    Research is still emerging on HMB. This means it’s vital that you take HMB only as directed to avoid any potential side effects or adverse events.

  • Does HMB prevent muscle loss?

    It might. Research has suggested that HMB may prevent muscle loss.

    HMB has been found to increase protein synthesis, an important step in building and maintaining muscle mass. One review found that HMB may help prevent muscle loss (atrophy) in older adults due to its ability to reduce protein degradation.

  • How long can you take HMB?

    You may be able to safely take HMB for up to 24 weeks. Additionally, some research shows that you may need to use HMB for at least two weeks to see positive results.

    More research may be needed on the long-term safety of using HMB, however, as very few long-term studies exist.

  • Is HMB a steroid?

    No. HMB is not a steroid. It is also not considered a performance-enhancing drug.

    Instead, HMB is a naturally produced substance that may act as an ergogenic aid. Ergogenic aids are substances, devices, or techniques that enhance athletic performance.

  • Does HMB cause hair loss?

    No. Hair loss is a possible side effect of various supplements, but there is no scientific evidence that HMB causes hair loss.

    Consult with a healthcare provider if you experience hair loss when taking HMB.

Sources of HMB & What to Look For

HMB can be found in both foods and supplements. Remember that your body makes HMB from leucine, and you can typically get plenty of additional HMB from a regular diet.

Some people choose to use HMB supplements for their potential benefits. A healthcare provider may also recommend HMB supplements for various reasons.

Food Sources of HMB

You can obtain HMB from a few foods. Your body can also make HMB from leucine, which can also be found in foods.

Foods like grapefruit, alfalfa, and catfish are said to contain HMB. However, these foods may only contain very small amounts of HMB.

Leucine is a part of most proteins and is more easily found in foods than HMB. Leucine is present in animal products in higher amounts than plant-based foods. You can find leucine in:

  • Beef
  • Pork
  • Chicken
  • Turkey
  • Dairy products
  • Fish
  • Legumes (beans, lentils, peas)
  • Grains (buckwheat, oats, millet)
  • Nuts (cashews, pine nuts, hazelnuts, almonds)
  • Certain fruits and vegetables

HMB is produced by the body when leucine is broken down. You may be able to increase HMB by eating more foods that contain leucine.

HMB Supplements

HMB supplements come in many forms, including capsules, powders, tablets, and soft gels. You can purchase these online, in certain grocery or retail stores, and in various supplement shops.

For the most part, HMB supplements are naturally gluten-free and vegan. Some products may also be organic. It’s important to note that HMB capsules made from gelatin are not vegan.

Keep in mind that supplements are largely unregulated by the Food and Drug Administration (FDA) in the United States. For this reason, some brands choose to have their products voluntarily reviewed by third-party agencies like NSF.org, ConsumerLab.com, and U.S. Pharmacopeia (USP). These agencies (and others) review supplement labels for accuracy and confirm that no contaminants are present.


HMB (hydroxymethylbutyrate) is a substance naturally produced by the body and also found in some foods and supplements. It is a by-product of leucine metabolism. HMB has been researched for its potential roles in muscle strength, exercise recovery, and the prevention of muscle loss. HMB shows some promise for these uses, but more research is warranted.

Talk with a healthcare provider if you have questions about HMB or if you’re thinking of using it.

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