Most Helpful Girl
We do it because we need reassurance sometimes especially from the guy who we're dating. When she asks that question tell her she looks beautiful in anything. Its basically just a time where we need a confidence boost or to know that we're not going out in public looking terrible. If she looks fat tell her no but suggest her wearing something else. By this I mean don't say "no you don't look fat, but you should wear something else" say "no you look gorgeous but I like the purple dress better."