Measuring energy expenditure has a significant role in health monitoring systems. It provides vital information about physical activities that are essential indicators of wellbeing, especially for children. Biofeedback systems are promising methods to monitor and measure daily energy expenditure. In this paper, we present a diet advisory system using biofeedback sensors to monitor children physical activities and estimate the consumed energy, which can be utilized to provide diet recommendations, based on children's health records and preferences, to the parents to improve the children's health status. We propose an algorithm to calculate daily energy expenditure for children based on the accelerometer sensor. This system aims to promote healthy food habits in accordance with energy expenditure, vitamins, and allergies. The system evaluation has demonstrated the ability of the proposed system to provide useful recommendations about the children diet habits for the parents while adopting to the children's health record and preferences and avoiding allergic food.