Anorexia nervosa is a dangerous and difficult-to-treat illness, but the most common problems may result from the lack of a clear distinction between competence and incompetence. There are a lot of studies which, on the one hand, suggest compulsory treatment of eating disorders; but on the other they underline the difference between resistance and refusal in the context of anorexia nervosa treatment. According to more flexible authors, anorexia nervosa is not included in the category of illnesses with psychotic symptoms and can't be treated under compulsory order, but when a person is in grave danger of dying it seems to be useful to treat such patients without consent. The main aim of the article is to present state of art literature about compulsory treatment, especially that concerning ethics and efficacy of such treatment. Additionally, the article presents modem attitudes to anorexic patients' treatment such as a new narrow definition of capacity and a guardianship resolution.