This amino acid metabolite gained a lot of press over the years and it's even been added to old-people meal replacement drinks, but does it work?
I was there when EAS introduced HydroxyMethylButyrate, better known as HMB, to the world. I didn't have anything to do with the actual research, sourcing, manufacture, or anything else you do when you introduce a new supplement to the world, but I was there, serving as the Editor-in-Chief of the company's magazine, Muscle Media 2000 (MM2K).
To my great embarrassment, though, I am partly responsible for the unofficial marketing slogan they used: "Feels like deca" (as in Deca-Durabolin, the anabolic steroid), but hear me out. I can explain (gulp).
The head of the company, Bill Phillips, had sent out some samples of HMB to various advisors and friends to get some input before releasing the product. I was in his office for an impromptu meeting when I noticed a fax on his desk. It was from the notorious, now deceased steroid expert, Dan Duchaine. The fax was in reference to HMB, and in the margin, in Dan's handwriting, were the words, "This stuff feels like Deca!"
Dan wasn't usually one for horseshit or hyperbole, so I told Bill, "Hell, this is how you should market HMB!" And so it happened.
While it would have broken all kinds of FDA rules to put it on the label, "feels like Deca" made it into articles about the product and maybe even an ad or two. That unofficial slogan still comes up mockingly on various internet threads and is usually greeted with howls of derision.
For all that, I'm truly sorry. Let me now say that HMB, unless you have AIDS, cachexia, or are bed ridden from some unspeakable disease, was never like Deca, and it still isn't.
What the HMB Research Shows
HMB is a metabolite of the amino acid leucine. When you ingest leucine, about 5% of it gets converted into HMB, and there seems to be pretty strong evidence that HMB has a greater effect in preventing muscle breakdown than actual leucine, at least in old or sick people.
However, there's little evidence that shows it works better than leucine in inducing muscle protein synthesis. One study found that 3.42 grams of HMB (3 grams is the standard, recommended dose) increased muscle protein synthesis by 70% while leucine itself increased it by 110% (1).
Another study, using athletes, did find that HMB increased muscle mass by 0.2+/-2.2%, over 9 weeks, but it didn't mean a whole lot because the participants had also increased their food intake by 8% (2). In all probability, they just ate bigly for a few weeks.
The most recent study in the literature, published just last month, also found that supplementation with HMB "failed to enhance body composition to a greater extent than placebo (3)."
Almost all of the other studies show either failure or fair-to-middlin' results, but even the ones that showed some promise were confounded by mitigating factors (an increase in calories, protein, or unpublished but alluded to dietary changes).
Where HMB does shine a bit, though, is in preventing muscle wasting, particularly in the aged, or those suffering from AIDS, cachexia, or are bedridden in general.
Studies to see if it works in preventing muscle protein breakdown in athletes are few and far between, though, and probably not relevant to weight lifters. One representative study designed to assess the effects of HMB in preventing female athletes (judo) from losing muscle during severe calorie restriction found that the supplement worked as well, or as poorly, as placebo (4).
Heals Bedsores 30% Faster!
HMB probably won't make anyone feel like they're on Deca, unless they're especially susceptible to the placebo effect, and it certainly won't work like Deca.
At best, it might help old (-er) people recover from illness, injury, or surgery, which is probably why the makers of Ensure, the people who make nutritional shakes primarily for old coots (if that's not their stated purpose, it's surely their main consumer demographic by sales) have put HMB into at least one of their formulas.
Lifters and athletes, whether they're interested in fostering additional muscle protein synthesis or in preventing muscle breakdown, would be better off ingesting whole proteins with a high protein efficiency rating like micellar casein, a whey isolate, or a blend of the two.
- Wilkinson, D.J., et al, "Effects of Leucine and its metabolite, b-hydroxy b-methylbutyrate (HMB) on human skeletal muscle protein metabolism, Journal of Physiology, 2013.
- Thomson, JS, et al, "Effects of nine weeks of beta-hydroxy-beta-methylbutyrate supplementation on strength and body composition in resistance trained men," J. of Strength and Conditioning Research, 2009.
- Felipe Texeiria, et al, "No effect of HMB or α-HICA supplementation on training-induced changes in body composition," European Journal of Nutrition, Dec. 27, 2018.
- Hung, Wei, et al, "Effect of b-hydroxy-b-methylbutyrate supplemenation during energy restriction in female judo athletes," Journal of Exercise Science and Fitness, Voll 8, issue 1, June 2010.