Eating disorders are surprisingly common amongst medical students. I don't think it will put you at a disadvantage, especially as it was years ago and you are fully recovered. However I agree with ForestCat - disclose it as appropriate on whatever forms you have to fill in, keep it professional and factual, and then only mention it otherwise if it was a significant factor in you wanting to study medicine. You could certainly put it across that way in your PS if you wanted to - talking about your stay in hospital and how you felt about those looking after you. That would be fine. But only if you want to. I wouldn't go with yhe 'still got decent grades despite mental illness' angle. While it is impressive, it's not the sort of thing that sounds good in an interview, and just invites questions you don't really want