Discovering New Insights Into Anorexia Nervosa: Influence of MicrObial DysbiosiS (DIAMOnDS)

Inclusion Criteria: * Women * Over 15 years old and 3 months. * Admitted in the specialized department for eating disorders of CHU Nantes for refeeding. * With a diagnosis of anorexia nervosa at admission (restrictive or Binge-Eating-Purging type). * Body Mass Index at admission below 16 kilogram per square meter. * Written informed consent for patients over 18 years old/ oral informed consent from both the patient and a legal representative for patients under 18 years old. * Affiliated with French social security system or beneficiary from such system. Exclusion Criteria: * Pregnant and breastfeeding women. * Who received a treatment with antibiotic/antifungal (other than local application) in the last three months. * Who had a weight gain in the last month (5% or more of the patient's weight at admission). * Under trusteeship or guardianship. * Not fluent in French * Who participate in another interventional study involving medication. * Patients for whom stool collection or body mass composition analysis (with Dual-energy X-ray absorptiometry) couldn't be done during the first week of hospitalisation.