OBJECTIVE: In Japan, the prevalence of overweight/obesity in the general population is considerably lower and the mean duration of hospitalization of patients with schizophrenia is much longer than those in Europe and North America. The aim of this study was to investigate whether these differences in ethnics or healthcare systems influence the nutritional status of patients with schizophrenia. METHODS: Body mass index (BMI) and blood biochemistry tests were determined at hospitalization and at discharge for 171 Japanese patients who were hospitalized for the treatment of acute phase schizophrenia. RESULTS: For 56 patients who were overweight/obese at hospitalization, BMI (p < 0.001), fasting plasma glucose (p = 0.039), and low-density lipoprotein (p = 0.027) were significantly lower at discharge than at hospitalization. BMI at hospitalization, duration of hospitalization, and age were associated with a decrease in BMI during hospitalization. Among the 115 patients who were not overweight/obese at hospitalization, there were no changes in BMI and blood biochemistry tests between hospitalization and discharge. CONCLUSIONS: Compared with inpatients, outpatients with schizophrenia may be more likely to be overweight/obese in Japan.