Depends how fat. Some skinny chicks are pretty hot, especially really little ones, but i tend to like taller girls and they are corespondingly larger. A bit of chub is ok, i dont demand a flat stomach or anything like that, but theres definetely a limit, i am just not sure where it is,
Obviously somewhere between "a bit fat" and obese but really, different people hold their weight differently so a two girls same height, same weight one will be acceptable and the other not.
Looks ofcourse come into it. As i have an extremely strange sense of humour, i am willing to forgive a lot for a girl who gets that, so a larger girl will get in the door easily if she finds jokes about cutting your own hole and raping it or baby plow jokes funny.