β-Hydroxy β-Methylbutyrate (HMB) is a dietary supplement that helps increase muscle strength and exercise performance. It also may help prevent muscle loss and protect the heart. Read below to learn if this supplement is worth the hype.
What Is HMB?
HMB, also known as β-Hydroxy β-Methylbutyrate (or β-Hydroxy β-Methylbutyric acid), is a popular bodybuilding supplement. Since the 1990s, athletes and bodybuilders have used HMB to build muscle and improve recovery from exercise .
- Improves exercise performance
- Improves muscle growth
- Prevents muscle loss due to aging and disease
- May help protect the heart
- No reported side effects or safety concerns
- Research results are mixed
- Not effective without exercise
- Less effective in trained athletes
1) Improves Strength and Exercise Performance
Many clinical trials have examined HMB’s effect on exercise performance and muscle growth.
What do these studies reveal?
A recent review searched through hundreds of HMB-related studies and identified 18 clinical trials that focused on exercise and muscle growth. These studies reveal several benefits, including :
- Increase in muscle mass
- Increase in strength
- Reduction of muscle damage
- Increase in anaerobic and aerobic performance
- Increase of lean body mass
The International Society of Sports Nutrition (ISSN) has also performed a critical analysis of the scientific literature. The ISSN concluded that HMB :
- Enhances muscle recovery after exercise in trained and untrained individuals
- Works when taken close to a workout
- Is most effective when taken for 2 weeks before heavy exercise
- Increases lean body mass and functionality in the elderly
But hang on a minute, a few things must be mentioned.
Research suggests that healthy people who do not exercise may see no benefit. Non-exercising individuals saw no changes to body composition or exercise performance .
Some studies also show that HMB has little effect on athletes who are already strength-trained. However, trained individuals may see some benefit if the exercise intensity is high enough .
What does this all mean?
2) Prevents Muscle Loss
Muscle loss commonly occurs in the elderly and in certain diseases.
Age-related muscle loss (also called sarcopenia) affects up to 10% of elderly people. This loss of muscle can lead to weakness and increased risk of falls .
An analysis of 7 trials including 146 older adults found that HMB effectively preserves muscle. There are increases in leg and handgrip strength as well .
Researchers also discovered that HMB supplements may prevent muscle loss caused by long periods of bed rest .
And there’s more. HMB may help in cachexia, which is muscle and weight loss caused by certain illnesses (like cancer and AIDS) .
Based on a review of 13 clinical trials, HMB shows several benefits, including :
- Increases lean body mass
- Improves immune status
- Decreases risk of death
- Reduces feeling of weakness
There are a few things to note.
Many of these studies used other supplements as well, including proteins and amino acids .
HMB was especially effective for cachexia caused by cancer, steroids, and immobility .
Also, these results were not universal – some clinical trials found no benefit compared to placebo .
3) May Protect the Heart
HMB may have antioxidant and anti-inflammatory properties that can promote heart health.
But there are a few problems. A recent comprehensive review of the scientific literature has revealed mixed results.
For example, some studies show that HMB reduces inflammation after exercise. However, almost an equal number of studies say otherwise .
In other words, the heart-protective effects of HMB may be due to an increase in exercise activity rather than the supplement itself .
How Does HMB Work?
But first, let’s talk about our muscles.
Our body is constantly building and breaking down proteins in our muscles. This continual process is how our body maintains its metabolism and energy .
When our body is in a state of building it’s referred to as anabolism. On the other hand, when our body breaks down molecules it’s called catabolism .
As you may expect, when anabolism is greater than catabolism there is a net gain in muscle protein .
HMB is often called an anti-catabolic, and for good reason.
HMB also may have anabolic effects, to a lesser extent.
Side Effects and Safety
In fact, rats didn’t experience side effects after taking a dose equivalent to a 180 lb man taking about 50 grams of HMB for 3 months .
A long-term long study in elderly people also did not find any safety concerns after taking HMB for a year .
However, there is one potential issue. HMB’s effects on muscle may decrease the availability of certain amino acids .
Limitations and Caveats
Research on HMB is not clear-cut. While many clinical trials are promising, a good number of studies have found conflicting results.
For example, one review identified 9 separate studies that show HMB has no effect in trained or untrained people .
It’s also important to note that the majority of studies use the calcium form of HMB (as opposed to the free acid form). Studies sometimes combine HMB with other types of supplements as well.
HMB Supplement Forms
HMB-Ca vs HMB-FA
Supplements generally combine HMB with calcium (Ca) to add chemical stability .
Usually, when we talk about HMB, we are actually referring to the HMB-Ca form. This is because, for a while, HMB-Ca was the only form of HMB available .
However, HMB in its free acid form (HMB-FA) has recently become commercially available. And there are important differences.
Here’s the best part. The plasma clearance of HMB-FA is 25% greater than HMB-CA. Plasma clearance indicates how fast the body is using up HMB. This implies that our body uses HMB-FA more quickly and effectively [23, 5].
But there’s a catch. The vast majority of clinical trials focus on HMB-Ca. The safety and effectiveness of HMB-FA is not as clear.
However, initial studies on HMB-FA do show the same promising effects on exercise and muscle .
Clear Muscle and BetaTOR
Clear Muscle is a popular supplement marketed as a muscle and strength builder.
The one and only active ingredient in Clear Muscle is a compound called BetaTOR.
What exactly is BetaTOR?
BetaTOR is a brand name for the free acid form of HMB, also known as HMB-FA.
Does it work?
Research does show that HMB-FA works quicker and reaches higher blood levels than HMB-CA .
The problem is there is far less research on BetaTOR compared to HMB-Ca. It’s unknown if the two forms have the same effectiveness and safety.
HMB is available as a combination product with creatine, another popular workout supplement.
One study shows that the combination increases lean body mass and strength. More importantly, this effect is greater than when either supplement is used alone. This suggests the effects are additive and there is a benefit to taking them together .
Other Supplement Forms
A variety of other HMB combination products are commercially available. This includes combos with BCAA, glutamine, L-Carnitine, and HICA.
Little to no research has been done on these combinations so it’s unclear if there’s a benefit to mixing these supplements.
HMB supplements are available as a capsule or powder.
Conveniently, supplements are typically available as 1 gram (1000 mg) capsules, to be taken 3 times a day.
When to Take HMB
HMB-Ca should be taken at least 60 minutes prior to exercise .
HMB-FA should be taken 30-60 minutes prior to exercise .
Supplements should be taken at least 2 weeks before increasing workout intensity or starting a new training period .
HMB Reviews & User Experiences
Online reviews of HMB supplements (including all forms and combinations) are generally positive.
Many users report seeing better muscle growth and recovery time after workouts. Some users report seeing benefits after just one week. Others have also seen great results when stacking with other workout supplements.
Negative reviews primarily consist of people who saw little to no benefit. Some users also report experiencing side effects including nausea, stomach pain, and diarrhea, especially from HMB-FA products.
Buy HMB Supplements
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HMB has good evidence for increasing muscle mass, strength, and exercise performance – but mainly when it’s combined with exercise.
You are most likely to see these benefits if you’re someone who is out of shape, but even if you’re an Olympic athlete, you may experience benefits if you train hard after supplementing HMB.
There isn’t enough evidence to conclude positive health effects for the heart or other conditions.
Despite mixed scientific evidence, anecdotal reports from users are generally positive.
HMB is generally very safe.
Those looking for a safe and natural bodybuilding supplement should try HMB, assuming you’re willing to do the heavy lifting!