Atypical Eating Disorders and Eating Disorders Not Otherwise Specified

Knowledge about atypical eating disorders is still limited although they are often associated with clinically relevant distress, negative effects on physical health, and reduction in quality of life. This chapter provides information about atypical anorexia nervosa, subthreshold bulimia nervosa, subthreshold binge eating disorder, purging disorder, night- eating syndrome, and the feeding and eating disorders pica, rumination disorder, and avoidant-restrictive food intake disorder. While some of these conditions often require treatment due to the strong fixation on weight and shape as well as persistent problems with eating and weight-regulating behaviors, others may not but still are associated with a reduction in quality of life, psychological distress, and sometimes dramatic negative effects on the physical health of those affected.