Life Extension Magazine®

Woman on yoga mat using HMB for boost in muscle growth

Preserve Muscle and Improve Body Composition

A derivative of the amino acid leucine, called HMB, improves muscle growth, strength, lean mass, and healthy body composition.

Scientifically reviewed by: Dr. Gary Gonzalez, MD, in August 2023. Written by: Michael Downey.

Americans are on a constant quest to improve body composition while increasing lean muscle.

It’s why we diet, jog, and hit the gym.

Now research has shown that there’s a compound that can help.

Beta-hydroxy-beta-methylbutyrate, better known as HMB, has been shown to improve muscle strength and quality in adults of all ages.1,2

It stimulates protein synthesis and prevents muscle breakdown.1

It even shows benefits in those who are practicing intermittent fasting while working out.3

HMB may help adults of any age achieve and maintain a healthier body composition.

Fat Vs. Muscle Mass

Woman building muscle mass

Having an ideal body composition isn’t just about looking good.

The ratio of fat versus lean mass in the body can be an excellent indicator of overall health.4

According to the Director of PEAK Health and Wellness at the University of Utah, maintaining a healthy body composition:4

  • Decreases the risk of cardiovascular disease, diabetes, and osteoporosis,
  • Lowers the risk of metabolic syndromes,
  • Maintains cognitive function and decreases stress,
  • Boosts energy, and
  • Enhances the ability to perform daily activities.

Being overweight and even aging itself are associated with a body composition of too much stored fat and not enough lean muscle mass.5

Body composition is influenced by our genetics, metabolism, or environment.6

As a result, researchers have been investigating ways to improve body composition.6

HMB Preserves Muscle

HMB (or beta-hydroxy-beta-methylbutyrate) is a compound formed naturally when your body breaks down the amino acid leucine.7

It’s been shown to help prevent sarcopenia,8 the age-related loss of muscle mass.

Scientists have demonstrated that HMB works by exerting pro-anabolic (muscle-building) and anti-catabolic (breakdown-preventing) properties.9-14

With age, HMB levels drop, a decline that correlates with diminished lean muscle mass and strength.15

A wealth of evidence has shown that HMB can protect, and even restore, lean muscle mass in older people.2,14,16-18

This led scientists to investigate whether HMB could protect or restore lean muscle mass in younger people— and whether it would work in those who are overweight or following muscle-decreasing fasting routines.

HMB in Overweight People

As of 2016, over 650 million adults worldwide suffered from obesity. This amounted to 13% of the world’s adult population at that time.19

Scientists designed a clinical trial to investigate the effects of HMB on muscle strength in overweight, sedentary women, aged 20 to 45. No exercise training was involved.1

The study was the most rigorous type: randomized, placebo-controlled, and double-blind (in which neither the subjects nor the researchers know who’s receiving the placebo or treatment).

Thirty-five women completed the study. All had a BMI (body mass index) between 25 and 29.9 kg/m2, considered overweight.

They were randomly divided into two groups. One was given 2.5 grams of HMB daily in two divided doses, while the other received a placebo.1

After six weeks, the results showed that taking HMB increased muscle strength in these women. Without any resistance training, they were able to lift heavier weights (with both arms and legs) than those in the placebo group.1

The study also concluded that HMB had a positive impact on various measures of body composition, including weight, waist and abdomen circumferences, and skin sagginess.1

HMB During Fasting

Woman using dumbbells and intermittent fasting

Another team of scientists investigated how HMB would affect muscle mass in people trying a form of intermittent fasting known as time-restricted feeding.

So scientists set up a randomized, placebo-controlled, double-blind study to test whether taking HMB could prevent this loss in those practicing this form of intermittent fasting.3

The research team recruited healthy female volunteers between 18 and 30 years old. All subjects were required to have previously participated in regular resistance training for at least one year.

These young, active women were divided into three groups:3

  • The control group took a placebo and maintained a normal eating schedule.
  • A second group took a placebo and followed a time-restricted eating schedule, which permitted eating only between noon and 8 p.m.
  • A third group took 3 grams of HMB daily and followed the same time-restricted eating schedule as group two.

All groups participated in a resistance training program for three nonconsecutive days each week.

What you need to know

Improve Body Composition with HMB and Vitamin D

  • Maintaining a healthy body composition is vital for overall health.
  • HMB (beta-hydroxy-beta-methylbutyrate), a compound formed when the amino acid leucine breaks down, has previously been shown to prevent muscle-wasting in older people.
  • New studies show that HMB preserves and increases lean muscle mass in adults of all ages. It also works in the overweight and in those on intermittent fasting programs.
  • Vitamin D has also been shown to produce significantly greater muscle strength and performance.
  • A combination of HMB and vitamin D could be a smart choice for anyone interested in maintaining optimal muscle mass and strength and achieving a healthy body composition.

After eight weeks, the researchers found in a subgroup analysis and compared to baseline that:3

  • The control group had an average 2% increase in body fat mass,
  • Group two had an average 4% decrease in body fat mass, and
  • Group three, the time-restricted eating group that took HMB, had an average 7% decrease in body fat mass.
  • The greatest increases in fat-free mass also occurred in the HMB participants, who had a shift to a healthier body composition.3

Vitamin D Supports Muscle Strength

Scientist studying vitamin c for muscle support

Like HMB, vitamin D also helps improve muscle strength and performance.20,21

Scientists conducted a study involving 160 menopausal women, aged 50-65, who all had a history of falling.22 Falling is associated with inadequate muscle mass, in addition to a lack of coordination and balance.23

The women were randomly assigned to receive either a placebo or 1,000 IU of vitamin D daily.

After nine months, the vitamin D group experienced a 25.3% increase in leg muscle strength.

Other investigators conducted a meta-analysis of 30 randomized, controlled trials, involving more than 5,600 people, to evaluate the effects of vitamin D on muscle performance.20

The analysis showed that vitamin D had a significant positive effect on overall muscle strength.20

Participants who had the lowest vitamin D levels at the beginning of the study (below 12 ng/mL) and those who were relatively older saw the greatest benefits from vitamin D supplementation.20

HMB Prevents Muscle-Wasting in Older Adults

Beginning around age 40, we lose an estimated 8% of muscle mass per decade. After age 70, muscle mass decreases by about 15% per decade.28

This drastic decline leaves people weaker and more prone to falls and other injuries.

The medical term for this loss of skeletal muscle mass is sarcopenia, and studies show that HMB can help prevent it.

A meta-analysis of seven trials involving a total of 287 older adults found that HMB preserved muscle mass in older adults. 17

One of the studies involved healthy older adults who voluntarily subjected themselves to 10 days of complete bed rest,18 a known cause of sarcopenia.29,30

Participants took either a placebo powder or a powder providing 1.5 grams of HMB, twice daily, starting five days before the bed rest period and continuing until the end of a rehabilitation phase.18

At the end of the 10 days, the placebo group had a reduction in total lean body mass of about 4.4 pounds.

By contrast, those taking HMB lost a total of just 0.37 pounds, showing a clear benefit in preserving lean body mass.

How Vitamin D Works

Woman supplementing with vitamin d for muscles

There are several ways in which vitamin D can have a beneficial effect on muscle.

Research has shown that vitamin D:

  • Directly increases the ability of muscle cells to contract,24,25
  • Improves the function and health of the mitochondria, the power suppliers in every cell, which increases muscle strength,26 and
  • Reduces chronic inflammation that can lead to muscle pain and weakness.27


Woman having smoothie for post workout

Maintaining muscle mass is vital for a healthy body composition.

HMB has previously been shown to reduce muscle wasting in older adults.

Human studies now confirm that HMB works in adults of all ages, promoting muscle growth and function while leading to improvements in strength, lean muscle mass, and body composition.

Vitamin D has been shown to boost muscle performance and strength as well.

Vitamin D and HMB can help improve body composition, preserve and increase muscle mass, and promote strength.

If you have any questions on the scientific content of this article, please call a Life Extension® Wellness Specialist at 1-866-864-3027.


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