The investigators aim at assessing peripheral concentrations of neuroendocrinological components of the Hypothalamus-Pituitary-Gonadal (HPG) and Hypothalamus-Pituitary-Adrenal (HPA) axis, as well as appetite-regulating hormones in AN and to examine associations with AN-associated psychopathology and neurocognitive performances before (baseline), during and after inpatient psychotherapy of female patients receiving concomitant treatment with estrogens (vs. placebo).