Systems and methods for estimating caloric expenditure. The systems can include a physiological sensor to measure a patients physical activity, and a posture sensor to measure the patients posture. An estimated caloric expenditure can be calculated based on data from the physiological sensor and the posture sensor. For example, the estimated caloric expenditure can be calculated at least in part based on the posture data. For example, the estimated caloric expenditure can be validated based on the posture data.