Latzer IT, et al. - Using bioimpedance analysis (BIA), researchers identified the threshold of total body fat percentage (TBF%) required for the resumption of menses (ROM) in hospitalized female adolescents with anorexia nervosa (AN). In a longitudinal prospective study 2012–2017, all female adolescents in the hospital with AN in the medical center were evaluated. Participants with ROM regained significantly more weight at discharge and had a higher mean body mass index (BMI), BMI standard deviation and TBF% vs with amenorrhea. In female adolescents with AN, BIA was a safe and relatively simple method to evaluate the TBF% required for the return of balanced menstrual cycles. It was observed that the TBF% with the highest discriminative ability for menstrual resumption as evaluated by BIA was 21.2%.