An eating disorder is a serious psychological condition. The sufferer is obsessed with food, diet and often body image to the point where their quality of life suffers, and their health is at extreme risk from their long-term poor or inadequate diet. Most victims of an eating disorder do not recognise that they have a problem and they will refuse treatment and attempt to hide their abnormal behaviour from others. Treatment of eating disorders can take decades, so early identification may be the difference between life and death for the patient.
The two major types of eating disorder which will be the most familiar to many are anorexia nervosa and bulimia nervosa. Binge eating disorder is similar to bulimia. Large amounts of food are consumed at a sitting but retained in the stomach rather than being regurgitated. Some experts consider a complaint called orthorexia to be a valid eating disorder - the sufferer is overly obsessed with the consumption of what they see as the 'right' foods for them (vegan, rawfoods, paleolithic etc), to the point where their nutrition and quality of life suffers. Some people have food phobias about what they can and can't eat, which may also be a form of eating disorder.