Abstract: A body composition measurement system (10) comprises: a body composition obtaining section (363) that obtains measured values of body composition of a user; and a positioning information determination section (364) that obtains positioning information, which is information indicating a position of the measured value of the user in a population. The body composition obtaining section (363) obtains the measured values by measuring the body composition of the user. The positioning information determination section (364) determines the positioning information using a positioning calculation formula or a positioning table stored in the memory unit (35). The positioning calculation formula or positioning table is prepared for each category such as age, gender, race, sport type, company, etc. The positioning information determination section (364) selects any category to determine the positioning information.

Abstract: A body composition change prediction device acquires a measured acetone concentration measuring acetone excreted from a user, acquires current body composition information and past body composition information of the user, computes a prediction value predicting the body composition information at a given future point in time based on information relating to the body composition of the user, and determines a fat burning style of the user based on the acetone concentration and the current body composition information. The body composition change prediction device weights the prediction value based on a weight, the weight being set according to the burning style and being a greater weight the higher the measured ketone body concentration, and outputs information according to the weighted prediction value.