The coordinating investigator left the sponsor institution and has not been replaced.

Anorexia nervosa is characterized by intestinal dysbiosis, related to the feeding behavior impairment presented by these patients. Pathophysiologic hypotheses are involving the trouble of the microbiota-gut-brain axis in the field of mental diseases.

Anorexia nervosa is characterized by intestinal dysbiosis, related to the feeding behavior impairment presented by these patients. Here we aim to characterize the IgA-coated fraction of bacteria from the intestinal microbiota, linked to the regulation of the mucosal immune system and the epithelium physiology. Abnormalities of this microbiota are reported in inflammatory bowel disease and are associated to immune trouble. As food intake plays a key role in shaping microbiota, we aim to correlate data from IgA microbiota to food intake specificity, and to anorexia nervosa phenotypes.

Inclusion Criteria:

• female subject, adult, affiliated to a social security system, under the care of the eating disorder department of university hospital of st Etienne
• presenting a diagnosis of pure restrictive anorexia nervosa.

For acute subgroup : BMI between 11 and 17.5 kg/m2, patient with a first episode of restrictive anorexia nervosa or with hyperphagic episodes.

For the chronic subgroup: BMI between 11 and 17.5 kg/m2, disease evolving for more than 5 years.

For Healthy volunteer: BMI between 20 and 24 kg/m², stable weight for the last 3 months, no eating disorder or history of eating disorder

Exclusion Criteria:

• patient does not understand French.
• laxative treatment in progress or stopped for less than 15 days,
• antibiotic treatment in the two months preceding inclusion,
• pre-pro or symbiotic treatment in progress or in the month preceding inclusion,
• patient with one of the following comorbid disorders: celiac disease, chronic inflammatory bowel disease, lactose intolerance, unstabilized hyperthyroidism, unstabilized diabetes,
• subject under legal protective measures.