How Does Weight Loss Resolve Obstructive Sleep Apnea?

It has been a well known fact that obstructive sleep apnea severity is directly correlated with weight gain or loss in adults. It's also why physicians often recommend weight loss as one of the ways to resolve obstructive sleep apnea (OSA). What has been less clear is exactly how weight influences sleep apnea until researchers at Univ of Pennsylvania examined the upper airway with MRI scans before and after weight loss.

It is tongue fat!!!

Researchers recruited 67 adult individuals with both obesity and OSA. MRI scans of the upper airway and abdomen were obtained before and after a weight loss intervention via intensive lifestyle modification or bariatric surgery. Airway sizes and soft tissue, tongue fat, and abdominal fat volumes were quantified on the MRI scans. Weight loss was found to be significantly associated with reductions in tongue fat, pterygoid, and total lateral throat wall volumes. However, reductions in tongue fat specifically were strongly correlated with reductions in sleep apnea severity.

Unfortunately, tongue fat was found to distribute diffusely throughout the tongue musculature and not in one concentrated location which makes liposuction not a viable treatment. But now that tongue fat deposits are known to be the root cause for triggering OSA with weight gain, further research can be pursued to target this area.

This may be the reason why throat exercises that target the muscles of the upper airway are known to help with obstructive sleep apnea, like blowing on a didgeridoo regularly. Read the research on this here.

References:
Effect of Weight Loss on Upper Airway Anatomy and the Apnea Hypopnea Index: The Importance of Tongue Fat. Am J Respir Crit Care Med. 2020 Jan 10. doi: 10.1164/rccm.201903-0692OC. [Epub ahead of print]

Effects of oropharyngeal exercises on patients with moderate obstructive sleep apnea syndrome. Am J Respir Crit Care Med. 2009 May 15;179(10):962-6. doi: 10.1164/rccm.200806-981OC. Epub 2009 Feb 20. 

Didgeridoo playing as alternative treatment for obstructive sleep apnoea syndrome: randomised controlled trial. BMJ 2006 Feb 4;332(7536):266-70. 

Risk of obstructive sleep apnea lower in double reed wind musicians. J Clin Sleep Med. 2012 Jun 15;8(3):251-5. doi: 10.5664/jcsm.1906.