How do I get my girlfriend to be healthy again?

Wow that sucks. I guess it sounds like kind of a turn around...did something happen in her life that was traumatic or upsetting to make her lose control/stop trying? I thin that if you work on whatever may be causing the lack of healthful thinking, it could help her eating habits. Make sure that she understands that you love her at whatever size, but you really want her to be healthy and ok.