One of my bridesmaids bought her dress too small, thinking it would motivate her to lose weight. We are roommates and have been trying to hold each other accountable for what we have been eating and such, so I have obviously been trying to encourage her not to eat such unhealthy things because A. she wants to lose weight anyway, and B. I want her to fit into her dress! Lately she has been getting upset with me for trying to persuade her not to eat certain things (like a milkshake). I realize the topic of weight is a sensitive issue for some people, but I really have tried to make it a point not to be too pushy about it because I don't want any feelings hurt....but then again, she isn't really trying and as of right now- and her dress won't even zip up.
How can I express my concern and slight frustration with the fact that this is going on without hurting her feelings too much? I don't want to ask her not to be in the wedding and I certainly don't want her to go through the embarrassment of not being in it because her dress won't fit or for her to wear an ill-fitting dress. I can't ask her to get another one later either because it has been discontinued.
I don't know what to do!