What is Beta-Hydroxy Beta-Methylbutyric Acid?

Optimum-HMB-FuelBeta-Hydroxy beta-methylbutyric acid, AKA HMB is a metabolite of the amino acid leucine, and it has been making the advertising rounds and has fired up the Internet rumor mill as a “new” muscle builder. Yet there are few studies to support it’s muscle building capabilities. The few studies there are were conducted by Steven Nissen, the inventor of HMB and owner of the patent.

There has been some unbiased research on HMB, conducted using resistance-trained men and not the elderly. The results here show HMB to be much less effective than Nissen claims.

  • A study conducted by the Singapore Sports Council found that HMB supplementation had no effect on strength or body composition in resistance-trained men.
  • A Massey University study found that HMB supplementation improved lower-body strength, but had negligible effects on body composition in resistance-trained men. Researchers from Massey University also conducted a literature review on the subject of HMB supplementation, and their conclusion was very simple (emphasis added):
    • “Supplementation with HMB during resistance training incurs small but clear overall and leg strength gains in previously untrained men, but effects in trained lifters are trivial. The HMB effect on body composition is inconsequential.”
  • A University of Memphis study found HMB supplementation did not reduce catabolism or affect training-induced changes in body composition and strength in experienced resistance-trained males.

So let’s sum it up:

1. It’s very good at preventing muscle breakdown, which means faster recovery and less muscle soreness. The free acid form seems to work the best here.

2. It has no effect on insulin levels, which makes it good for those who like to do fasted training.

3. Its powerful anti-catabolic (prevent or minimize the breakdown of muscle) effects and lack of insulin effects means you can get the fat loss benefits of fasted training without muscle loss or insulin secretion.

4. HMB is superior to leucine in suppressing muscle breakdown. This means it’s also more effective than branched-chain amino acid supplements because they rely on leucine for their anti-catabolic effects (isoleucine and valine are very weak in this regard).

What all this means is HMB supplementation can offer some muscle preserving effects for lifters trying to maintain muscle mass while losing weight.

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