Hydroxymethylbutyrate (HMB): Benefits, Downsides, and More

Athletes and fitness enthusiasts are always looking for ways to improve their performance.

And while the right combination of diet and exercise can help fuel that performance, certain supplements may offer additional benefits.

HMB is a popular dietary supplement that has gained a lot of interest in the health and fitness community for its potential to aid muscle growth and exercise performance.

This article explains what HMB is and outlines its potential benefits. It also provides information on its safety and other recommendations.

HMB is a substance your body produces naturally.

It has a few different names, depending on the version of the molecule. It’s also known as:

• beta-hydroxy beta-methylbutyric acid
• beta-hydroxy beta-methylbutyrate
• hydroxymethylbutyrate

However, since the body only produces HMB in small amounts, many people take it as a dietary supplement to increase their HMB levels.

HMB is widely available in supplement stores, health food stores, and online. It comes in various forms, such as a capsule, tablet, or powder.

Studies link taking HMB supplements to certain benefits, such as:

• increased muscle growth in untrained and older adults
• reduced muscle breakdown
• increased exercise performance

But some of the research has been mixed or inconclusive. Additional research may be needed to fully understand the effects of HMB in various populations.

Let’s take a closer look at what the research says about the promising benefits of HMB.

Companies commonly market HMB as a supplement that aids muscle growth. While research is mixed, some studies suggest HMB may benefit muscle growth and strength in certain populations.

For example, a 2024 study found that HMB supplementation might help people with sarcopenia, a type of age-related muscle loss, though the evidence was limited. And a 2022 meta-analysis of nine studies also found benefits for older adults.

Another 2022 study found limited evidence that HMB may help improve muscle mass in people with cancer.

Other studies have found that HMB doesn’t influence muscle growth.

For example, a 2019 review of 10 studies examined the effects of HMB in 384 adults ages 50 and over. Researchers found that combining HMB supplements with physical exercise had little to no effect on changing body composition, strength, or exercise performance compared with exercise alone.

A 2018 analysis of 6 studies involving 193 participants found that HMB may not improve these factors for trained and competitive athletes, either. Researchers found that when athletes took 3 to 6 grams of HMB daily for 3 days to 12 weeks, they experienced no increases in strength or changes in body composition.

Research suggests HMB may help reduce muscle breakdown.

Test-tube studies suggest that HMB may help prevent muscle breakdown in various ways inside cells, such as by suppressing genes and enzymes that promote the breakdown of muscle proteins.

An analysis of 15 studies looked at the effects of taking HMB in 2,137 people. These participants had health conditions that promote muscle loss, such as cancer, HIV, kidney failure, and malnutrition.

The analysis found that taking 3 to 4 grams of HMB daily for 7 days to 6 months was significantly more effective than a placebo at preventing muscle loss.

Similarly, other studies in older adults have shown that taking HMB can help preserve muscle mass, especially during periods of bed rest.

However, before recommending it for this purpose, more research is needed on HMB’s potential protective effects against muscle breakdown in a wider variety of participants, such as young people and healthy adults.

Some research suggests that HMB could improve adaptations to exercise. This refers to a longer-term change rather than an immediate one.

For example, a 2015 study of 16 elite rowers found that taking 3 grams of HMB daily over 12 weeks significantly increased aerobic exercise capacity and peak anaerobic power, and helped reduce body fat, compared with a placebo.

Anaerobic power refers to the maximum power you can produce during high intensity exercise.

Similarly, another 12-week study in 42 combat sports athletes found that taking 3 grams of HMB daily significantly increased both aerobic and anaerobic exercise capacity compared with a placebo.

HMB may have other benefits, too, including:

Studies have examined other potential benefits, such as improvements in cardiovascular health, but results have been mixed or inconclusive.

Summary

Studies have linked HMB to various health benefits, such as improved exercise adaptations, reduced muscle loss, better exercise recovery, and more. It may also increase muscle growth in untrained people and older adults.

In rare cases, people may experience stomach pain, constipation, or itching while taking HMB.

Although there’s no standardized dosage for HMB, most studies have used 3 grams per day. A 2019 review recommends that dosage for 3 to 4 weeks for competitive athletes. Researchers have not studied the safety of long-term use of HMB.

As with any dietary supplement, it’s important to speak with a healthcare professional before taking HMB, especially if you are on medications or have preexisting health conditions.

Summary

HMB appears to be generally safe in standard doses of 3 grams daily. As with any dietary supplement, speak with a healthcare professional before taking HMB.

HMB plays an important role in regulating protein production in the body. Because muscles are primarily made of protein, it can help build muscle mass or prevent muscle loss.

HMB typically does not cause side effects. However, some people in clinical trials did report adverse events, like gastrointestinal symptoms.

HMB and creatine are supplements that may both help with muscle growth. However, they’re distinct compounds.

Research from 2020 found that HMB produced a small gain in total body mass in adults ages 18 to 45. However, whether HMB causes you to gain weight will depend on several factors, including the type of exercise you do.

HMB is a substance your body produces naturally when it breaks down the amino acid leucine.

It may offer benefits when some people take it as a supplement.

Some evidence suggests it may help reduce muscle loss and aid exercise adaptations. It may also increase muscle growth in untrained people and older adults.

Other potential benefits include aiding exercise recovery and reducing inflammation and age-related mental decline.

HMB may offer additional benefits when combined with creatine, vitamin D, and other amino acids, such as glutamine and arginine. These combos may aid muscle growth and performance, increase muscle strength, and help prevent muscle loss, respectively.

It’s important to note that more research is needed on many of these potential benefits.

HMB appears to be safe in standard doses of 3 grams daily, although researchers have not studied the effects of long-term use. As with any dietary supplement, speak with a healthcare professional before taking HMB.