Obesity prevention requires individuals to have healthy eating and physical activity awareness in their daily lives. New technological products have been explored to help monitoring individual health behaviors. Smart phones are ubiq-uitous hand-held tools with rich embedded sensors and limited computing power. A smart phone is a prospective candidate to integrate physical exercise analysis and food intake monitoring. This paper presents a novel health-aware smart phone system (HealthAware) which utilizes the embedded accelerometer to monitor daily physical activities and the built-in camera to analyze food items. The system presents the user's physical activity counts at real time to remind how much daily activity is needed to keep healthy. The user takes pictures of food items and the system provides health related information regarding to the food item intakes. The system is composed of an on-device database which holds the user specific data and food item information. HealthAware is a real time practical system to prevent obesity by enhancing individual daily healthy behavior awareness.