Anorexia is a serious mental disturbance, whose symptomatic feature is egosyntonicity. It means that the afflicted person derives their sense of identity from it. The costs of the disorder are less outstanding for them than its advantages. Egosyntonicity influences the patients' attitude to their disorder and treatment considerably, and therefore also - the course of anorexia. Anorexics usually believe that they are healthy, or assume that anorexia is very attractive for them. Thus resistance to treatment is one of the most important problems, which clinicians treating anorexia nervosa must cope with. Heated debates have been hold around the account of capacity and compulsory treatment in anorexic patients. They result mainly from the fact that the current conception of capacity, which is based on understanding and reasoning seems to be inadequate for patients with anorexia nervosa, for whom the disorder guarantees maintaining their sense of self. Therefore, it appears that identity should be considered as a relevant factor in the assessment of capacity of these patients, depending on how it affects their ability to make decisions.