Anorexia nervosa is a multi-aetiological specific eating disorder with psychological, sociological and somatic symptoms and complications. Apart from psychotherapy and pharmacotherapy, concomitant nutritional rehabilitation plays an important role in the treatment of anorexia nervosa. According to well-established specialists in the treatment of eating disorders, the multidisciplinary treatment team should include a qualified dietician who will be responsible for planning, conducting and controlling the nutritional therapy and nutritional re-education of patients and their family members. The course of diet therapy in the management of anorexia is phased, tailored to each case and must be adapted to the current physiological and psychological state of the patient. Diet therapy must take into account multiple factors such as: the patient’s current clinical status, eating habits and preferences as well as their motivation to cooperate in treatment. The latter is extremely important in the management of anorexia nervosa. The aim of this study is to present the role and the goal of nutrition therapy in the treatment of anorexia nervosa and to describe possible benefits of a reliable diet therapy. A detailed characteristics of diet therapy including planning and the description of changes in the dietary scheme in the course of treatment is provided. The study also presents practical guidelines for nutritionists which can help improve the nutritional therapy.