The obesity epidemic is a major health concern. More than two thirds of Americans and more than one third of children and adolescents are overweight or obese. Physical inactivity and sedentary lifestyle are contributing factors of overweight and obesity. Increasing physical activity in overweight and obese individuals can potentially improve health status and lower the risk of major health problems. Based on the theoretical frameworks of behavioral change models, health information technologies, and pervasive interactive technologies, a conceptual model has been developed. The proposed model is an intervention method combining a behavior change model and a personalized Health IT system using an interactive accelerometer-based pervasive technology component, to increase physical activity potentially in an overweight and obese population. The accelerometer automatically synchronizes with the personal health record database over wireless networks; the decision engine utilizes the theory of planned behavior model to form a feedback; and; proper interactive feedback is provided directly to the users in the personal health record interface. A prototype was developed based on the conceptual model. The prototype measures and stores the number of steps, type of steps and caloric consumption on a daily basis with an interval of 20 minutes by an advanced accelerometer that can simply be attached to any footwear. The accelerometer synchronizes automatically the stored data with a central database as soon as the participant enters a designated wireless area. Virtual characters that are embedded inside a personal health record system convey the feedback to the users. The feedback is generated based on the theory of planned behavior decision model utilizing the stored daily physical activity data. The interface prompts knowledge-based information, presents self-monitoring trend lines, and shows virtual character changes over time such as becoming obese, to reflect the tailored feedback message. In addition, the interface is integrated in a popular social-networking website where users can review other virtual characters and generate peer pressure. The purpose of this study is to explore the feasibility of implementing a behavioral change intervention using pervasive health information technology among overweight and obese population. This research explains the development of the conceptual model, integration of wireless physical activity self-monitoring devices into personal health records, and the application of rich interactive media to convey messages to the users. The final prototype will be presented and preliminary findings will be discussed.