In my case, it was those blue eyes I'm such a sucker for and the cool moustache and cute Southern accent that first got my attention.
But hey - as much as we'd all like to lose weight to be healthier, etc., that usually doesn't matter in the long run, attraction-wise. At least for me, I find that the people I'm drawn to have kindness, humor, intelligence, interesting life experiences, etc. -- much more important than what their packaging looks like.
It's funny, but I've always found that the better friends I become with someone, the better-looking they become to me, no matter what size they are. It's nice to have all good-looking friends.