June 6, 2011 -- A medicine used to treat asthma may also be a fat-burning drug, new research suggests.
When taken in pill form, the drug known as formoterol boosted fat burning while preserving protein metabolism, thus maintaining muscle mass, says researcher Paul Lee, MD, PhD, of the Garvan Institute of Medical Research and an endocrinologist at St. Vincent's Hospital in Sydney, Australia.
"Fat burning was increased up to 25%," he says of his study results. "But the amount of protein burned is less [than without the pill].''
That could be good news for people trying to shed fat and for people who have noticed an age-related decline in muscle mass, he says. "It can promote a loss of fat while preventing the inevitable loss of muscle," Lee tells WebMD.
Lee presented his findings Saturday at the Endocrine Society's annual meeting in Boston.
Two experts in obesity treatment who reviewed the findings say the research is promising. However, they also say the findings are preliminary and the study is small. The effects, if they bear out, might be more noticeable in the way clothes fit than in numbers on the scale, says Frank Greenway, MD, an obesity specialist at the Pennington Biomedical Research Center in Baton Route, La.
Formoterol is used as an inhaled medication for asthma and chronic obstructive pulmonary disease (COPD). Lee used it in pill form, giving eight men, on average 30 years old, 160 micrograms a day for one week.
Before and after the study, he measured the men's energy rates, fat oxidation, and whole body protein metabolism.
Each time, the measurements were taken after the men drank a standardized, high-carbohydrate liquid meal, Lee says.
"Comparing their before and after rate, their [overall] energy rate increased by more than 10%," he says. "Fat burning was up about 25%. But the amount of protein burned was less. The person burns less protein and more fat."
Theoretically, he says, an average person weighing 155 pounds could burn an extra 200 calories a day with the pill. Over time, that could translate to noticeable fat loss and maintained or gained muscle.
"If we lose more fat than muscle, that's a good thing," Lee says.
The inhaled form of the drug can cause an abnormally fast heartbeat, but Lee did not see this side effect in the men who took the pill form.
"Some had insomnia, but it was mild," he says. It was also temporary. "Some reported loss of appetite."
In addition to burning fat, the drug might prevent or treat muscle wasting that can accompany age. "It may potentially reverse or prevent this process and treat frailty," Lee says.
The National Health Medical Research Council Australia funded the study.