[영문]OBJECTIVE:S: Significant weight gain is a serious side effect of many antipsychotic medications, yet successful strategies for significant weight loss are lacking. The transtheoretical model for weight management can be used to identify people who are ready to change (contemplation-preparation group) their eating habits and physical activity. This study compared characteristics of patients in Canada who had a psychotic disorder and were ready to make lifestyle changes with characteristics of patients who were not considering lifestyle changes. METHOD:S: Participants were surveyed to determine their stages of change for eating habits and physical activity, and various characteristics were measured, including body mass index, body image, nutritional intake, and level of physical activity. RESULTS: A total of 101 participants (64 men) (mean±SD age 35±11 years) were taking antipsychotic medications. Seventy-one percent had schizophrenia spectrum disorders, and 15% had affective psychosis. The prevalence of patients identified as being ready for change was higher than expected: 68% for eating habits and 54% for physical activity. Participants who were ready to change eating habits were also ready to change physical activity habits (pqqqlt;.04). Stages of change for eating habits were associated with body mass index (pqqqlt;.004), whereas stages of change for physical activity were associated with self-reported vigorous (pqqqlt;.001) and moderate (pqqqlt;.005) physical activity but not mild physical activity. CONCLUSION:S: Clinicians may help patients develop healthier eating and physical activity habits by using the transtheoretical model, because it identifies patients who are ready to change to healthier lifestyle strategies and may help patients with antipsychotic-induced weight gain.