Context - Objective: To assess the role of body composition and to determine the threshold of total body fat mass and trunk fat mass, required for menstrual recovery in adolescents presented with secondary amenorrhea and diagnosed with Anorexia Nervosa, as well as to investigate their impact in psychopathology of these girls. Methods - Patient(s) - Intervention(s): Prospective study of 60 adolescents presented with secondary amenorrhea and diagnosed with AN. Anthropometrics, body composition by dual-energy X-ray absorptiometry, hormonal studies and responses to mental health screens (EAT-26), were obtained at the beginning and at complete weight restoration, in all adolescents, independently of menstrual recovery (Group A) or not (Group B). Main Outcome Measure(s) - Result(s): At the end of short-term complete weight restoration, Group A total body fat mass, trunk fat mass and trunk / extremities fat ratio were significantly higher (p < 0.001) than Group B. Menstrual resumption was expected in 20% of total body fat mass (% of total body tissue) and 20% of trunk fat mass (% of total trunk tissue). At time of menstrual recovery, total body fat mass (%) and trunk fat mass (%) were significantly negatively correlated with EAT-26 (r=-0.363, p=0.032) and (r=-0.416, p=0.013) respectively, while an increase of 0.40% of trunk fat mass (%) lowers EAT-26 by one unit. Conclusions: A minimum of 20% of total body fat mass and 20% of trunk fat mass (% of total trunk tissue) is mandatory for menstrual recovery, after complete weight restoration, while distribution of fat in the trunk can positively influence psychopathology of these girls.