In healthy men aged 67 to 69, taking 3 grams of HMB-free acid daily while doing strength training led to a slightly greater increase in thigh muscle mass compared to a placebo, though the difference was not large enough to be considered statistically certain.

We analyzed the available evidence on HMB and muscle mass in older men doing resistance training, and what we’ve found so far is limited but points in one direction. One study in healthy men aged 67 to 69 found that taking 3 grams of HMB-free acid daily, along with strength training, led to a slightly greater increase in thigh muscle mass compared to a placebo [1]. However, the difference was small and not large enough to be considered statistically certain. We did not find any studies that contradicted this result, and the single assertion we reviewed supports the idea that HMB might help slightly with muscle gains in this group. But because only one assertion was analyzed, and the effect was modest and not statistically certain, we cannot say whether this outcome would hold true for other older men, or if it would make a meaningful difference in daily life. HMB-free acid is a compound related to the amino acid leucine, which the body uses to build muscle. Taking it as a supplement may help support muscle repair during training, especially when natural muscle-building processes slow with age. Still, the evidence we’ve reviewed is very thin — just one study, with a small and uncertain effect. For older men considering HMB while lifting weights, the current data doesn’t rule it out, but it also doesn’t strongly confirm it. If someone chooses to try it, they should expect only a small potential benefit, and not rely on it as a major driver of muscle growth. More research is needed to know if this effect is real, consistent, and worth the effort.