I wouldn't, just like I wouldn't reject a skinny girl. I'm not in the best shape (not bad, but not the best), and I think it would make me feel good, because an attractive person liked me (attractive in the sense that they're this culture's current ideal, and therefore prolly think of themselves as attractive, and so them choosing you generally means that they think you're about as attractive as they are. Hope that makes sense).
Honestly, if he was skinnier than me, he would literally be ridiculously skinny or child sized. I'm only 119 lbs so yeah it'd be really unattractive if he was skinnier than me, not due to insecurity, but because it would just look gross to me, frankly.
My boyfriend is skinnier than I am and I think he's very attractive. I don't think looks should really play a huge factor although they do help. The reason I decided to be with my boyfriend is simple he gives me the same respect I give him and he takes the time out of his day to message me cute little notes and when I need him he's there provided he isn't in the middle of something important
i weight 175 I wouldn't want to be with some one thinner than me because it's awkward i I was 160 and i was heavier than him it made feel uncomfortable i felt huge and when we had sex i felt like i could break him was not a good feeling