When I arrived at the sleep clinic with a BMI of 22, the first thing they told me was: there are lots of people with sleep apnea who have a healthy weight, including children.
The notion that sleep apnea is generally caused by weight needs to die. People also conveniently forget that being woken up multiple times every hour causes weight gain, so often times being overweight is the consequence of sleep apnea rather than the cause.
What's crazy is all the downvoting. Why are people so invested in this idea that BMI is the primary/sole cause of OSA? It's literally killing people and the science is pretty conclusive. It should be one of those screens you take at certain milestone ages like colonoscopies.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5181619/