You don't simply get one. It's not a physical choice. In fact an eating disorder forms mostly from a distorted body image and refusal to maintain a "normal" weight.
I have an emotional eating disorder and the best thing anyone can do for me is listen to me complain about stuff so it doesn't stress me out. If I get stressed I eat. I guess it depends on what type...
With an easting disorder, a person can experience many health probelms. Some common ones inclde hari loss, fatigue, weakness, fainting, dizziness, low heart rate, low blood pressure, depression, OCD,...