Abstract In treating patients with severe anorexia nervosa, it is important to improve their physical condition first. Patients who had lost close to 60% standard bodyweight (SBW) were candidates for inpatient treatment due to the mortality risk. With 80% SBW as the target for therapy, they were given both intravenous hyperalimentation and food by oral intake in order to improve their physical condition. In total, 51 patients were admitted. One died and four patients dropped out in the course of treatment. Forty-six patients who completed the inpatient treatment were reviewed. Although admitted with an average weight of approximately 60% SBW, they were discharged with a weight of approximately 80% SBW after approximately 60 days. An average follow up of 25.0 months was conducted, and two patients were found to have died. The mean weight, percentage resuming menstruation, and rehospitalization rate of the 44 survivors were 79% SBW, 23%, and 32%, respectively. The patients with the restricting type of anorexia had an earlier onset of the disorder and a better social outcome. Patients in whom onset occurred at a younger age had a better social outcome. After being discharged, the majority of the patients continued treatment as outpatients. Although the results were similar to those of conventional studies in terms of outcome, the shorter hospitalization was significant. Overall, in the treatment of patients with severe anorexia nervosa, it is important to begin psychotherapy while trying to improve their physical condition.