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 spiralled out of control. Severe distress or concern about body weight or shape may also characterize an eating disorder. Eating disorders frequently appear during the teen years or young adulthood but may also develop during childhood or later in life. Common eating disorders include anorexia nervosa, bulimia nervosa, and binge-eating disorder.