A method for automatically identifying users of a body-fat meter includes following steps: measuring body information of a user through a measuring unit of the body-fat meter； obtaining multiple user accounts registered in a memory； respectively reading a personal data and multiple historical body values relative to each user account； calculating a predicted value for each user account based on the measured body information and the personal data of each user account； determining if any of the user accounts has the multiple historical body values that are matching with its corresponding predicted value； and, storing the corresponding predicted value for the matched user account for updating the multiple historical body values of the user account.
