Objective: Anorexia nervosa (AN) is a complex psychiatric disorder characterized by persistent dieting and reduced food intake, leading to significantly low body weight. Dysbiosis in the gut microbiome of patients with AN has been suggested to contribute to the pathogenesis. Here, we used fecal microbiota transplantation (FMT) in the activity-based anorexia (ABA) rat model to investigate the impact of AN-associated gut microbiota on disease-related outcomes.
Method: We validated the FMT in 12 Wistar rats by depleting the gut microbiome with antibiotics and transplanting two donors' fecal samples. We then transplanted fecal samples from four patients with AN or four healthy controls in 48 rats just before the ABA model exposure and included an antibiotic-only control group. During ABA, the rats had access to a running wheel and only 1.5 h access to chow for 7 days. We monitored body weight, body temperature, food intake, wheel revolutions, and gut microbiome biodiversity and composition.
Results: The antibiotic treatment significantly depleted the rats' gut microbiome and subsequent transplantation made the rats' microbiome more similar to the donors' microbiome. The antibiotic-only group showed reduced survival, as well as lower body weight and temperature during ABA. Transplanted microbiota from patients with AN and healthy controls improved outcomes in the ABA model.
Discussion: We do not find evidence that the microbiome of patients with AN differentially contributes to anorexia-like phenotypes based upon partial microbiome transplantation. However, the presence of a microbiome impacts the outcome of the ABA model.
Keywords: activity‐based anorexia model; anorexia nervosa; fecal microbiota transplantation; microbiome depletion; microbiome dysbiosis.
© 2025 The Author(s). International Journal of Eating Disorders published by Wiley Periodicals LLC.