Research has proven that losing weight is a reliable way to treat sleep apnea in overweight patients.

Swedish researcher Kari Johansson led a randomized control trial that examined the effects of weight loss on sleep behavior. Researchers looked at 63 men with a body mass index between 30 and 40. From this group, 30 men were randomly selected to follow a low-calorie liquid diet for seven weeks. After seven weeks, participants were reintroduced to solid food over the course of two weeks. The remaining obese men in the study were used as a control group and were not asked to change their diet or exercise patterns in any way.

The study monitored the apnea-hypopnea index (AHI) of all of the participants. The AHI reflects the average number of times each hour that a person stops breathing or experiences shallow breathing during sleep. When the study began, the average AHI for both groups was 37, which is considered severe obstructive sleep apnea. After the study, the average AHI of the group of dieters had dropped to 12, which is considered mild. The group that had not been on the liquid diet maintained an average AHI rating of severe.

Researchers noted that the Swedish study provided “the first high-quality evidence that moderate-severe obstructive sleep apnea can be treated with weight loss.”