This study aims to investigate possible different outcomes in the inpatient treatment of anorexia nervosa (AN) related to different timings of psychopharmacological and nutritional interventions. A retrospective observational study was conducted, involving young patients hospitalized for AN, treated with naso-gastric tube feeding (NGT). Participants were divided into five groups according to early (0-7 days) or late (8+ days) introduction of atypical antipsychotics (AAP) and NGT: early AAP-early NGT (EE), early AAP-late NGT (EL), late AAP-early NGT (LE), late AAP-late NGT (LL) and a control group treated with NGT only (NGT). Concurrent clinical and treatment variables were analyzed. AN psychopathology was measured with the Eating Disorder Inventory-3 (EDI-3) EDRC score. Outcomes were assessed as admission-discharge body-mass index (BMI) improvement and length of hospital stay (LOS). Contributions of variables related to outcomes were assessed with multifactorial-analyses of variance (MANOVA). Seventy-nine patients were enrolled in the study. LOS was different among treatment groups (F (4, 75) = 5.993, < 0.001), and EE patients showed lower LOS than LE ( < 0.001) and LL ( = 0.025) patients. BMI improvement was not significantly different among treatment groups but correlated negatively with age (F (1, 72) = 10.130, = 0.002), and admission BMI (F (1, 72) = 14.681, < 0.001). In conclusion, patients treated with early AAP and early NGT showed lower LOS than those treated with late AAP. Prognostic treatment variables should be investigated in wider samples.