A fat-reduction weight-loss method, comprising: firstly, locally heating a site in need of fat-reduction under 37 to 60°C until the blood and muscles separate from the fat then, locally freezing the site in need of fat-reduction under -10 to 5°C until the fat solidifies. Also disclosed is a weight-loss instrument using the fat-reduction weight-loss method, comprising: an input unit (A) for receiving a user operation and outputting a signal representing the user operation to a control unit (B) a control unit (B) for outputting a heating signal or a freezing signal to a heating and freezing unit (C) according to the received signal representing the user operation and a heating and freezing unit (C) for receiving the heating signal or freezing signal of the control unit (B) and conducting the heating or freezing operation. The fat-reduction weight-loss method at first locally heats the site in need of fat-reduction to separate the blood and muscles from the fat at the site in need of fat-reduction, then instantaneously freezes the site in need of fat-reduction to solidify the fat, thus avoiding the harms such as tissue necrosis and the like caused by the solidification of the blood and muscles together with the fat in the freezing fat-reduction process.
