Obesity is a risk factor for many health problems, but a new Penn Medicine study published this month in the journal Sleep suggests having a larger tongue with increased levels of fat may be a sign of obstructive sleep apnea (OSA) in obese adults.

The researchers examined tongue fat in 31 obese adults who had OSA and 90 obese adults without the condition. All subjects underwent magnetic resonance imaging and the size and distribution of upper airway fat deposits in their tongue and upper airway muscles measured.

The data also showed a correlation between tongue fat volume and sleep apnea severity, and with body mass index. The researchers believe that increased tongue fat may explain the pathogenic relationship between obesity and sleep apnea.

“Previous studies showed that the human tongue has a high percentage of fat, and that tongue fat and tongue weight were positively correlated with the degree of obesity,” said study senior author Richard J. Schwab, MD, professor of Medicine in Penn’s Perelman School of Medicine and member of the Center for Sleep and Circadian Neurobiology. “This is the first study that examined OSA patients and found higher fat deposits in obstructive sleep apnea patients than in those without OSA.”