I don't think girls can be underweight unless they're anorexic and yes I agree that there is somebody for everybody.
But romantic idealistic notions aside. I'm saying you can increase your chances of getting more guys to like you if you were of a lower weight. Hence, you would have more choices of guys to choose from and be able to pick a better guy.
Lol it's impossible to represent my view in this thread without coming off as a complete ass. Well then again there's some truth to that. lol!