Researchers in Virginia have identified a drug that has increased muscle mass in older, frailer people.

A once-daily dose of the drug MK-677 increased overall body weight by nearly six pounds compared with a placebo, which only managed a 1.8-pound increase. Additionally, study participants regained some 20% of the muscle mass they had lost through the normal course of aging. The study was conducted over the course of two years by researchers at the University of Virginia Health System.

The drug is designed to stimulate a certain growth hormone receptor, which in turn increases appetite. Researchers say the study shows the future potential for so-called “anti-frailty” pills. Their research appeared in Tuesday’s issue of the Annals of Internal Medicine.