As a supplement, the amino acid leucine has long been known to support the synthesis of new muscle. Because of this, it also supports increased muscle size, strength, and in turn reduces body fat. Not many supplements can boast such claims. One issue, however, that plagued researchers for some time was the required dosage of leucine to reduce muscle proteolysis. Proteolysis means the breakdown of proteins into their constituent parts. Basically, it means your muscles getting smaller, and leucine prevents this, but only in doses much higher than its other benefits.
Researchers then determined the reason for the discrepancy in leucine doses for its varying effects was that it was actually a metabolite of leucine that helped prevent proteolysis. They eventually determined that it was beta-hydroxy-beta-methylbutyrate, which comes from leucine, that kept the reins on proteolysis. This chemical is better known in the supplement community as HMB.
In 1996 the first study demonstrating the effects of HMB on proteolysis was released. Since that time numerous studies have supported the effects of HMB supplementation for athletes, but their results have been mixed. In response, the International Society of Sports Nutrition released its official stand on HMB after critical analysis of the history of research. Below are the major things they uncovered.
Qualities of HMB:
- Enhances recovery for both trained and untrained people.
- Provides greatest benefit when consumed close to a workout.
- Seems to increase in effectiveness if taken for weeks at a time even when not exercising.
- Works best at about 38 mg/kg of bodyweight (84 mg/lb).
- Comes in two forms, calcium bonded and free form, the latter of which might be better but needs more study.
- Assists elderly people in developing muscle better, which is critical to their health.
- May increase fat loss
- Increases muscle building as well as inhibits muscle breakdown
- Is safe for long term use in young all the way through older populations
It’s worth noting that some of the authors of this analysis have received funding from public or private sources in the past. Some have also been paid to speak on behalf of supplement companies. While we should take this review for what it is, HMB does seem to be a supplement worthy of consideration for the lofty status that other proven supplements like protein powders and creatine have attained. I’d like to see a review like this one performed by a collection of unbiased researchers as well.
One thing is clear. Despite some varying results in past studies the results are, nevertheless, generally positive in the ways that you want a good supplement to be positive. The disagreement lies in where HMB is most beneficial, and how beneficial is it. As such, HMB is worth adding to your basket at the supplement store and giving it a good try to find out for yourself if it’s worth it for you.
1. Jacob Wilson, et. al., “International Society of Sports Nutrition Position Stand: beta-hydroxy-beta-methylbutyrate (HMB),” Journal of the International Society of Sports Nutrition 2013, 10:6
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