I was diagnosed with moderate sleep apnea 5 years ago and the doctor suggested I get outfitted with a CPAP. I asked if it was possible to reduce or eliminate sleep apnea with lifestyle changes, and he stated that in rare cases, some people have done so with aerobic exercising. I interpreted that to mean weight loss, and I went strict low carb (under 20 grams of carbs daily) that day. I had a follow up visit 6 months later, and I found I no longer had sleep apnea after losing 40 pounds in that time frame. While I take fitness seriously today, I did not radically increase my workouts during that time, and I attribute my success in avoiding CPAP to strict low carb & related health improvements including weight loss.