A Study on the Effects of Combined FMT on Gut Microbiota and Eating Disorder Symptoms in AN

Inclusion Criteria: * Female, aged 12-35 years, meets DSM-5 diagnostic criteria for anorexia nervosa. * BMI \> 14 kg/m²; for children/adolescents, BMI \> the 0.3 percentile for their age. * Presence of digestive symptoms (e.g., constipation, bloating, diarrhea). * Duration of the disease (since the onset of dieting and weight loss) is less than two years. * Each patient must understand the nature of this study and sign an informed consent form. Exclusion Criteria: * Co-morbid severe mental disorders such as schizophrenia, bipolar disorder, intellectual disability, persistent delusional disorder, schizoaffective disorder, or organic mental disorders. * Substance abusers/addicts, individuals with a high suicide risk, or those with strong destructive impulses or antisocial behavior. * Those with severe low body mass anorexia nervosa (e.g., blood pressure \< 80/50 mmHg, heart rate \< 40 beats/min, weight loss \> 1 kg per week, or those requiring assistance in sitting or squatting in a prone position). * Patients with severe somatic diseases or comorbidities, including: * Organic intestinal lesions such as congenital megacolon, intestinal obstruction, or intussusception. * Previous pathological intestinal inflammatory conditions such as inflammatory bowel disease. * History of traumatic brain injury, cerebral palsy, encephalitis, or other organic brain disorders. * Severe hepatic or renal insufficiency (defined as levels greater than three times the upper limit of normal). * Pr…