The present invention relates to a smart tray for measuring a food intake and a weight change, and a weight management system comprising the smart tray, the smart tray comprising: a weight sensor for detecting the weight of an object placed on the upper surface and generating object weight information; an input unit for inputting the current weight information of an eater; and a control unit for controlling the weight sensor, generating weight deduction information, which is a value deducted from the object weight information, as food intake information within a predetermined time, and, by using same, generating estimated changed weight information.