A wearable weight detection system includes a first wearable device, a second wearable device, and a processor, wherein the first wearable device and the second wearable device directly contact a user's skin. The first wearable device emits a minute current through the user's body and is received by the second device. The second wearable device calculates the impedance value of the user based on the received minute current and transmits the impedance value to the processor. The processor calculates the body composition ratio value of the user based on the impedance value and calculates the weight changes of the user in comparison with an initial body composition ratio value. Compared with the prior art, the present invention uses the change of the user's body composition ratio to calculate the weight changes, and can estimate the user's current body weight and body composition without the weight scale.一種穿戴式體重檢測系統，其包含一第一穿戴式裝置、一第二穿戴式裝置以及一處理器，其中第一穿戴式裝置以及第二穿戴式裝置直接接觸一使用者之皮膚。第一穿戴式裝置發出一微小電流通過使用者體內傳導並且由第二裝置所接收。第二穿戴式裝置依據所接收的微小電流計算使用者之阻抗值並將阻抗值傳送給處理器。處理器依據阻抗值計算使用者之身體組成比例值，並且與一初始身體組成比例值比較計算使用者體重變化量。相較於習知技術，本發明利用使用者身體組成比例的變化推算體重變化量，可以在沒有體重計的情況下估算使用者目前體重以及身體組成。
