Anorexia nervosa is a mental health disorder typical for adolescent girls and young adults. The clinical picture is often characterized by distorted body image and intense fear of gaining weight or becoming fat in spite of actual underweight. It is associated with severe disturbance of psychological, physical and social functioning. When the patient strongly resist all weight gaining measures clinicians may have to consider the possibility of involuntary treatment. In the Finnish Mental Health Act there are different definitions for involuntary treatment in adults as compared with under-aged patients. In adults the core question is whether anorexia nervosa can be defined as a psychotic disorder or not. The present review also summarizes literature concerning benefits and disadvantages of involuntary treatment in these patients.