Most Helpful Guy
It would be a red flag. In fact it would be a serious red flag. It isn't necessarily a deal breaker.
The reason being is that I would feel sad that she is behaving in a way that's self destructive. I wouldn't want to see her get sick due to her disorder. I would want her to seek help.
If I knew that she was seeking help, I'd probably date her. If not, then I would not date her.