What is HMB?

HMB is short for beta-hydroxy-beta-methylbutyrate. It is a popular exercise supplement, and it is a metabolite of leucine. Leucine is a branched chain amino acid (BCAA) known for its effectiveness in building muscle and improving exercise performance.

But our bodies break down just 5% of leucine to form HMB through the process of oxidation. HMB is the main metabolite of leucine which is beneficial in slowing down the breakdown of muscle protein1.

Health Benefits

This compound is called an anti-catabolic agent as it slows down the process of catabolism, which is when muscle proteins are broken down. Levels of the enzyme plasma creatine phosphokinase indicate when muscle proteins have been damaged. These levels are lower when taking HMB supplements2.

By reducing muscle damage during exercise, it helps you recover from workouts faster so you can get back to training hard. In this way, it also helps you build up more muscle mass and increase your muscle strength3.

Leucine vs. HMB

Being a breakdown product of leucine, you would expect leucine and HMB to have similar properties. But on a gram per gram basis, HMB is more effective than leucine at slowing down how fast muscle proteins are broken down. To be exact, it is 20 times more effective than leucine for its anti-catabolic properties. However it is not as effective as leucine at stimulating muscle protein synthesis.

Find out more about leucine and other BCAAs here

Dietary Sources

To boost your leucine levels which in turn increases how much HMB your body naturally produces, the best options are meat, eggs and fish. Grapefruits also contain this compound. 4. If you are a vegetarian or want to supplement your dietary intake, taking supplements in tablet or powder form is another option.

Supplement dosage

We naturally produce 0.2-0.4g of HMB in our bodies each day. The recommended daily dosage of HMB supplements for their anti-catabolic function is 1- 3g per day. Taking this compound in addition to creatine monohydrate is also popular as their benefits increase when taken together5. But for muscle protein synthesis, the best choice is leucine which is more effective and cheaper.

When should I take it?

Take HMB just before the training session to increase its availability in your blood stream. This allows your body to use the compound to respond better during the workout.

It is safe when taken in the recommended dosages. However if you have any health problems it is best to check with your doctor that any supplements will not interact with any medications you are taking.

VIDEO: Guide to HMB

For privacy reasons YouTube needs your permission to be loaded.
I Accept



  1. Examine.com. HMB. 2018. Available from: https://examine.com/supplements/hmb/
  2. Panton LB, Rathmacher JA, Baier S, Nissen S. Nutritional supplementation of the leucine metabolite beta-hydroxy-beta-methybutyrate (HMB) during resistance training. Nutrition. Internet. 2000. 16(9):734-739. Available from: http://www.sciencedirect.com/science/article/pii/S0899900700003762
  3. Nissen SL, Abumrad NN. Nutritional role of the leucine metabolite beta-hydroxy-beta-methylbutyrate (HMB). Journal of Nutritional Biochemistry. Internet. 1997. 8(6):300-311. Available from: http://www.sciencedirect.com/science/article/pii/S095528639700048X
  4. Maxi Nutrition. HMB Side Effects Internet. 2018. Available from: https://www.maxinutrition.com/nutrition/advice/HMB-Side-Effects/
  5. HMB.org. HMB in combination. Internet. 2018. Available from: http://www.hmb.org/about-hmb/science-instead-of-hype/hmb-in-combination/