Many of a range of psychological disorders characterized by abnormal or disturbed eating habits (such as anorexia nervosa). An eating disorder is an illness that causes serious disturbances to your everyday diet, such as eating extremely small amounts of food or severely overeating. A person with an eating disorder may have started out just eating smaller or larger amounts of food, but at some point, the urge to eat less or more spiraled out of control. Severe distress or concern about body weight or shape may also signal an eating disorder. Common eating disorders include anorexia nervosa , bulimia nervosa, and binge-eating disorder.