Abstract: The authors, considering domestic and foreign studies of cognitive rigidity/flexibility and ideas about one's own body in anorexia nervosa, note the practical lack of research on both dynamics and ideas about the existence and nature of the connection between these psychological characteristics of girls suffering from anorexia nervosa. The object of the study was psychological characteristics, namely, mental rigidity, cognitive flexibility and the attitude of teenage girls suffering from anorexia nervosa to their bodies. The subject of the study was the change in the level of rigidity/flexibility and negative attitude towards one's body, as well as their relationship during inpatient treatment of anorexia nervosa. Objectives of the study: to identify changes in the characteristics of mental rigidity and attitude to one's body, as well as in the nature of the relationship between cognitive rigidity, flexibility and attitude to the body from the beginning to the end of inpatient treatment of adolescents suffering from anorexia nervosa. Teenage girls (13-17 years old) with a diagnosis of anorexia nervosa participated in the study conducted at the Center for the Study of Eating Disorders (CIRP) in Moscow. Used: the classic J. R. Stroop test, a simplified version of the Tomsk rigidity questionnaire, a questionnaire of cognitive flexibility, a questionnaire "Attitude to one's body". A factor analysis of the relationship of the studied parameters was carried out. A special contribution of the authors of the study is proof that a negative attitude towards one's body in anorexia nervosa, both at the beginning and at the end of inpatient treatment, positively correlates with a high level of rigidity and a low level of flexibility, as well as the fact that the nature of this relationship fundamentally changes from the beginning to the end of inpatient treatment. The novelty of the study lies in the discovery that from the beginning to the end of inpatient treatment, a shift in the psychological problem occurs: low cognitive flexibility, as well as the inability to identify with one's body, cease to be the main problem, and a negative assessment of the attractiveness of one's body for oneself comes to the fore, which at the end of inpatient treatment should become a specific target for psychotherapeutic work. The practical significance of the study lies in the fact that it allows to identify the targets of psychological work (psychotherapeutic, correctional, rehabilitation) and their change from the beginning to the end of inpatient treatment.