Being overweight can cause sleep apnea, BUT there are lots of people out there who have it and they aren't fat or obese. I got to quarterly sleep disorder seminars and I usually get people glaring at me because I am "skinny" compared to them. I could lose 30 lbs, but these folks could use hundreds of pounds!
I tried sinus surgery and that didn't work so I just use a CPAP machine now. 99% of the people use the humidifier with theirs, I'm the 1% who can stand the dry mouth and deal with it. Advantage is have never needed to wash the hoses and masks every few days. Heck, I haven't washed my mask for 6 months and aside from some cat hair stuck on the outside due to static, it looks brand new.
I find if I take sometime between dinner and bed time it can mess me up so I can't fall asleep until later.
Sleep apnea is no joke - you will DIE a young age if you don't address it sooner than later. I found out I had it because my wife told me I stop breathing and she ends up elbowing me so I take a breath.
It is a pain to go do a sleep study - they superglue sensors all over your head and hair and when they send you home you still have to pick the darn glue off yourself over the next couple of days. This is how they learn what pressure setting to use to keep your air way open so you can breath correctly and get REM sleep. I use a full face mask because it works if I open my mouth with the nose ones and air hisses out and wakes me up.