Little is known about the association between polyunsaturated fatty acids (PUFAs) and eating-related patho-physiology in anorexia nervosa (AN). The aim of this study was to determine whether nutritional treatment with enteral formula, rich in PUFAs, affects (1) the concentrations of PUFA and brain-derived neurotrophic factor (BDNF) in serum, and (2) the depressive symptoms and eating-related pathophysiology in patients with AN. Thirteen patients with AN par-ticipated in this study. Serum PUFA and BDNF concentrations were measured before and after receiving the enteral for-mula, and eating-related psychopathology and depressive symptomatology were assessed using the eating disorder inven-tory-2 (EDI-2) and the Hamilton Depression Rating Scale (HDRS), respectively. Body mass index (BMI) and HDRS scores showed significant improvement after treatment. Patients receiving the nutritional treatment, enteral formula with enriched PUFAs, favorably adhered to the treatment, and showed significant improvements in BMI and depressive symp-toms. Randomized controlled studies are required to further examine the effectiveness of PUFAs in AN.