The goal of the study was to elucidate the relationship between serum circulating brain-derived neurotrophic factor (BDNF) and body weight reduction via lifestyle modification and behavior therapy in obese non-diabetic patients with chronic schizophrenia. Thirty-three obese non-diabetic subjects with schizophrenia treated with stable antipsychotic medication in a day-care unit for at least 3 months were recruited. Thirty age-, body weight-matched subjects without psychiatric disorders were enrolled as controls. All participants underwent a 10-week weight reduction program, including lifestyle modification, psychosocial treatment, behavior therapy and exercise in the day-care unit. Blood biochemistry, serum BDNF, adipokine (adiponectin), inflammatory markers (C-reactive protein, tumor necrosis factor-alpha and interleukin-6) and oral glucose tolerance test were evaluated before and after the program. Serum BDNF concentrations were significantly lower among patients with schizophrenia compared to control subjects. Serum BDNF levels were significantly increased following the weight reduction program. Elevations in serum BDNF levels were positively correlated with body weight and body mass index reduction. Altogether, our results demonstrate that a non-pharmacological weight reduction program effectively reduces body weight with significant elevation of serum BDNF levels in obese non-diabetic patients with schizophrenia.