Yes, obesity is on a scale for the medical profession. I can’t name all the steps but it’s basically severely underweight, underweight, normal weight, overweight, obese, severely obese. As far as the cohort, sleep apnea is often a side effect of obesity, though not always caused by it (see central apneas which is a nervous system disorder).

Sleep apnea compounds obesity because it makes it difficult to get restful sleep, which is one of the necessary tools for losing weight.