Losing weight is an effective treatment for obstructive sleep apnea (OSA), but why exactly this is the case has remained unclear. Now researchers in the Perelman School of Medicine at the University of Pennsylvania have discovered that improvements in OSA symptoms appear to be linked to the reduction of fat in one unexpected body part—the tongue.
Using magnetic resonance imaging (MRI) to measure the effect of weight loss on the upper airway in obese patients, researchers found that reducing tongue fat is a primary factor in lessening the severity of OSA. The findings were published in the American Journal of Respiratory and Critical Care Medicine.
“Most clinicians, and even experts in the sleep apnea world, have not typically focused on fat in the tongue for treating sleep apnea,” says Richard Schwab, MD, chief of Sleep Medicine, in a release. “Now that we know tongue fat is a risk factor and that sleep apnea improves when tongue fat is reduced, we have established a unique therapeutic target that we’ve never had before.”
A 2014 study led by Schwab compared obese patients with and without sleep apnea and found that the participants with the sleep disorder had significantly larger tongues and a higher percentage of tongue fat when compared to those without OSA. The researchers next step was to determine if reducing tongue fat would improve symptoms and to further examine cause and effect.
The new study included 67 participants with mild to severe obstructive sleep apnea who were obese—those with a body mass index greater than 30.0. Through diet or weight loss surgery, the patients lost nearly 10% of their body weight, on average, over six months. Overall, the participants’ sleep apnea scores improved by 31% after the weight loss intervention, as measured by a sleep study.
Before and after the weight loss intervention, the study participants underwent MRI scans to both their pharynx as well as their abdomens. Then, using a statistical analysis, the research team quantified changes between overall weight loss and reductions to the volumes of the upper airway structures to determine which structures led to the improvement