Background. Antipsychotics exert metabolic side effects, and prolonged treatment with antipsychotics causes changes in body weight and muscle composition. Nevertheless, reports on the changes in body composition of patients with schizophrenia have been limited. This study is aimed at comparing the body mass index and body composition of patients with schizophrenia with healthy individuals in Indonesia. Methods. A total of 195 patients with schizophrenia (148 males and 47 females) and 195 healthy individuals matched by gender were recruited. Using the Bioelectrical Impedance Analysis method, the participants’ body compositions were measured. Results. Compared to healthy individuals, the patient group exhibited a higher rate of underweight as well as a lower rate of overweight and obesity. Multiple regression analysis confirmed the associations between the body mass index and all measured body compositions. Furthermore, the diagnosis of schizophrenia is significantly associated with lower muscle mass, lower bone mass, higher basal metabolic rate, older metabolic age, and higher total body water. Conclusions. The results showed that patients with schizophrenia are at a greater risk of a lower quality of certain components of body composition. Priority should be given to research that addresses increasing the patient’s level of physical activity.