Obesity is a major risk factor for obstructive sleep apnea (OSA), which is characterized by frequent stopping of breathing during sleep (from a few seconds to 20 seconds or more) and, besides loud snoring, is associated with hypertension, heart disease, diabetes, depression, osteoporosis, and increased mortality, among other adverse consequences. And it’s long been recognized that weight loss is effective in reducing symptoms, though how exactly has not been clear. A novel study in the American Journal of Respiratory and Critical Care Medicine in January 2020 has elucidated a possible answer: It might have to do with tongue fat.
Building on previous research at the University of Pennsylvania in 2014—which found that obese people with OSA had bigger and fatter tongues than obese people without OSA—the same team of investigators followed 67 obese people with this sleep disorder for six months, during which time they lost almost 10 percent of their body weight, on average, with corresponding improvements in apnea symptoms. MRI scans of the participants’ upper airway soft tissue structures and abdomen, done before and after the weight loss, revealed that those who had the greatest reductions in tongue fat (but not abdominal fat) had the most improvement in OSA.
This was true after the amount of weight loss was controlled for, suggesting that “reduced tongue fat is independently associated” with symptom improvement. Losing tongue fat “should improve muscle function [of the tongue] and could prevent collapsibility during sleep,” the researchers wrote.
Among other findings: Reductions in the pterygoid and pharyngeal lateral wall (muscles in the jaw used for chewing and on the sides of airways, respectively) seen on the MRI scans were also linked with OSA improvements, though to a lesser degree than tongue fat.
The results of the study suggest that tongue fat could be a potential new target for OSA treatment. But more research is needed to better understand the mechanisms by which weight loss specifically affects soft tissues in the throat, to determine how prevalent “fatty tongues” are in people who are not obese, and to see whether certain weight-loss strategies are better than others for decreasing tongue fat—for instance, different diet interventions, physical activity, upper airway exercises, surgery, or cold therapy (which breaks down fat cells and is currently used for reducing abdominal fat).
This article first appeared in the UC Berkeley Wellness Letter.