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β-Hydroxy β-Methylbutyrate (HMB) is a dietary supplement that helps increase muscle strength and development. It can also help with exercise 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 dietary supplement. Since the 1990s, athletes and bodybuilders have used it in order to help them with building muscle.

It is a chemical that is naturally produced in the liver and muscle when the body breaks down the amino acid leucine, arguably the most important of the essential amino acids for muscular development (R).

Leucine is well-known and a widely investigated amino acid due to its broad effects, including important roles in protein metabolism, glucose homeostasis, insulin action, and recovery from exercise (R).

Some of the benefits from leucine are from HMB (R).

Health Benefits of β-Hydroxy β-Methylbutyrate

1) HMB Helps with Exercise

HMB supplementation increases strength and lean body mass by acting as an anticatabolic agent; it minimizes protein breakdown and damage to cells that may occur with intense exercise (R, R1, R2).

Supplementation with HMB can enhance gains in lean body mass, muscle size (muscle hypertrophy) and muscle strength (R).

Supplementation appears to speed recovery in both trained and untrained individuals if the exercise stimulus is of high intensity, and/or high volume in nature (R).

HMB may affect cellular receptors and hormones, such as cortisol, testosterone, and insulin, and even the modulation of enzymes responsible for muscle breakdowns. It can reduce muscle damage that occurs during exercise (R, R1, R2).

2) HMB Reduces Muscle Loss

Muscle loss is common during aging and in chronic diseases, leading to decreased physical function, a decreased quality of life, and increased mortality.

Recent evidence suggests that HMB can improve conditions characterized by muscle wasting such as cancer and AIDS, and to promote wound healing following surgery or injury (R, R1, R2).

This supplement is effective in reducing or even reversing the loss of muscle mass, muscle strength and muscle function that characterizes those diseases. Additionally, supplementation can be an alternative for individuals under extreme muscular stress and by elderly individuals to prevent muscle wasting (R, R1).

3) HMB Protects the Heart

This supplement also lowered total cholesterol, low-density lipoprotein cholesterol, and blood pressure. This demonstrates potential cardioprotective effects and decrease of the risk of heart attack and stroke (R).


  • Increases IGF-1 (R, R1, R2)
  • Increases mTOR (R, R1, R2)
  • Inhibits ubiquitin-proteasome system (R, R1, R2)
  • Increases synthesis of cholesterol (in sarcolemma) (R, R1, R2)


HMB is available as an over-the-counter dietary supplement.

The utility of HMB does seem to be affected by the timing of intake prior to workouts and dosage (R).

Finally, in order to optimize long-term effects that HMB has, the recommendation would be to consume 3 g daily. It should be divided into three equal servings two weeks prior to a potentially damaging skeletal muscle event (R).


There are no potential side effects when supplementing with 3–6 grams of HMB daily. Additionally, HMB is safe if taken over the course of several months (R, R1).

Pregnant and lactating women should not take HMB.



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