People diagnosed with obstructive sleep apnea are often told to lose weight as part of their treatment plan. New research shows that reducing fat in one particular part of the body can provide the most significant symptom relief.

If you guessed the tongue, take your place at the head of the class.

Research has shown losing weight can improve a person’s Apnea/Hypopnea [hy-POPE-nea] Index, the leading measure of obstructive sleep apnea. In the new study, researchers at the University of Pennsylvania used MRI to measure the effect of weight loss on the upper airways of obese patients. Those who lost 10% of their body weight over six months through diet or weight-loss surgery improved their AHI scores. More importantly, about 30% of that improvement was linked to reduced tongue fat.

Previous research found patients with obesity and sleep apnea have larger tongues and higher percentages of tongue fat compared with those without sleep apnea.

Targeting tongue fat, however, isn’t easy. You have to lose weight throughout your body to see results. The researchers suggested, however, that exercises to strengthen tongue muscles or therapies like cool sculpting may be worth exploring.

The findings also might help explain why surgery to reduce the size of the tongue, called coblation, has not been effective for treating sleep apnea. Coblation vaporizes soft tissue but does not discriminate between tongue muscle and tongue fat.

For the 22 million Americans diagnosed with obstructive sleep apnea, the new findings add an important piece to the puzzle of what’s keeping them from getting a good night’s rest.