New study reveals complex relationship between obesity and obstructive sleep apnea

A new international analysis has revealed important insights into the two-way relationship between obesity and obstructive sleep apnea (OSA), reinforcing the need for a broader approach to identifying and managing the condition.

Published in April 2025, the study examined data from four community-based cohort studies in the US and Switzerland, involving 12,860 adults with an average age of 66.6 years. It found that while obesity is a well-known risk factor for OSA, the majority of people with OSA are not living with obesity.

Researchers used the apnea-hypopnea index (AHI) to assess OSA severity, measuring episodes of disrupted breathing that lead to oxygen desaturation. Overall, 56.2 per cent of participants were found to have OSA (AHI ≥5 events/hour), and 25.7 per cent had obesity (BMI ≥30 kg/m²).

The analysis showed that only 31.5 per cent of those with OSA were also living with obesity, while 44.4 per cent were classified as living with overweight and 23.5 per cent had a BMI in the normal or underweight range. Meanwhile, 74.3 per cent of individuals living with obesity and 59.8 per cent of those who were overweight were found to have some degree of OSA.

Notably, obesity was more prevalent among women with OSA compared to men, and higher in those under 65 years of age. Individuals living with overweight and obesity were 2.18 and 4.84 times more likely, respectively, to have OSA than those with a BMI under 25.

The findings challenge common assumptions and emphasise that while obesity remains a significant risk factor for OSA, it is not a prerequisite for developing the condition. The authors call for a more nuanced, individualised approach to OSA diagnosis and treatment, particularly in populations that may not be traditionally considered at risk.