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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.



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).

Evidently, some of its benefits are from its metabolites (products from its breakdown) including HMB. Therefore, supplementation with HMB is more likely to induce a greater increase in muscle gain as opposed to supplementation with leucine (R).

Health Benefits of β-Hydroxy β-Methylbutyrate

1) HMB Helps with Exercise


HMB supplementation influences strength and lean body mass by acting as an anticatabolic agent; it minimises 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 efficient 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).


  • Recent studies have proposed a series of mechanisms by which HMB acts; (1) upregulation of IGF-I gene -commonly known to help build muscle- expression in skeletal muscles (R, R1, R2)
  • (2) The stimulation of protein synthesis and muscle hypertrophy by increasing the rapamycin (mTOR) signaling pathway (R, R1, R2).
  • (3) The suppression of proteolysis by the inhibition of the ubiquitin–proteasome proteolytic system (R, R1, R2).
  • (4) The increase in the synthesis of cholesterol needed to form and stabilize the muscle membrane (sarcolemma) (R, R1, R2).
  • The first form is a calcium salt form (HMB-Ca, empirical formula: Ca (HMB)2-H2O) which is  in a capsule form (R).
  • Notably, administration of HMB in the free acid form results in a faster increase of the HMB levels in the blood (R, R1).


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.

Where to Buy HMB

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The information on this website has not been evaluated by the Food & Drug Administration or any other medical body. We do not aim to diagnose, treat, cure or prevent any illness or disease. Information is shared for educational purposes only. You must consult your doctor before acting on any content on this website, especially if you are pregnant, nursing, taking medication, or have a medical condition.


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