The present invention provides fat detect device, fat detect system and user matching method, the fat detect device includes a measurement unit which is used to measure the user physiological state to obtain current weight and current impedance as an current analytical data set, a storage unit which is used to cumulatively store the user names with the user character information and the recorded analytical data set including recorded weight and record impedance, a processing unit which makes the user name associated with the user, then uses the current analytical data and the user character information to obtain body fat information.一種體脂量測裝置、系統及配對方法,其中體脂量測裝置及系統包括:量測單元,用以量測使用者的現時體重及現時阻抗作為現時分析資料組;儲存單元,用以累積地儲存用戶名稱、與用戶名稱相應的用戶特徵資訊和複數個包括紀錄體重及紀錄阻抗的紀錄分析資料組;以及處理單元,用以配對與使用者相應的該用戶名稱,並讀取與該用戶名稱相應的該用戶特徵資訊,同時結合該現時體重及該現時阻抗以計算取得一體脂資訊。S11~S16‧‧‧步驟
