What is HMB?

In the UK, 1 in 7 of us hold a gym membership.¹ Whether we’re lifting in the weight room or taking part in an intense HIIT class, more and more of us are looking for ways to improve our overall fitness and wellbeing.

With this in mind, it’s unsurprising that many of us look to supplements and fitness aids to improve the effects of our workouts. Whether you regularly browse the shelves in your local sports store or look online for training tips, you might have seen some information about HMB.

If you’re wondering whether HMB is the right type of supplement for you, you can find everything you need to know below.

What is HMB?

HMB is a type of molecule that’s produced when your body processes an amino acid called leucine.² Its official name is beta-hydroxy beta-methylbutyrate, but you’ll likely see it on the shelves as ‘HMB.’

HMB is naturally produced by your body, which means you may not need to supplement it. However, some people choose to take it in higher dosages for a range of reported benefits.³

HMB supplements are usually sold in capsule or powder form. They might be mixed with other ingredients or sold as single-ingredient products. There are currently two forms of HMB available: Calcium HMB (HMB-Ca) and a free acid form of HMB (HMB-FA). At the moment, there isn’t a lot of evidence to say which one is better.⁴

What does HMB do?

Like with any supplement, it’s essential to proceed with caution when adding HMB to your health routine. While research is underway, it’s not always clear how taking additional supplements will interact with the body. If you have any concerns, it’s best to speak to your doctor first.

As a by-product of leucine, it’s thought that HMB can help to reduce or prevent the breakdown of muscle.⁵ There are other associated benefits, which might include:

• Muscle loss⁶
• Muscle strength⁷
• Muscle gains⁸
• Reduced blood pressure⁹
• Athletic performance¹⁰
• Heart health¹¹

However, it’s worth noting that studies are quite limited on the overall effects of HMB.

In terms of muscle gain and strength, some studies have suggested that HMB is most useful for people unused to exercise or strength training. It’s not clear how well HMB supplements would work for people who already weight train.^12,13

Potential side effects

On the whole, it’s thought that HMB is a reasonably safe supplement for most people.¹⁴ It’s always a good idea to talk to your doctor before taking it, especially if you are on other medications.

While clinical studies haven’t revealed concerning side effects, it’s also worth remembering that this doesn’t mean there aren’t any.^15,16

Last updated: 24 March 2021