The principle of human body fat scale is that muscle contains more water such as blood and can conduct electricity, while fat is not. Because the channel conductor of current in the body is muscle, the weight of muscle can be known from the difficulty of current passing, so as to judge the proportion of muscle in the weight.
It is found that when an electrical signal with a certain frequency passes through the human body, the "impedance value" of the fat part is higher than that of muscles and other tissues of the human body. When an electrical signal with a safe specific frequency passes through the human body, the electrical signal will change in different degrees due to the different "impedance values" of the human body.
Principle: Muscle contains more water such as blood, which can conduct electricity, but fat can't. Because the channel conductor of current in the body is muscle, the weight of muscle can be known from the difficulty of current passing, so it can be judged that people with less muscle have a higher proportion of fat.
Refer to the above content: Baidu Encyclopedia-Body Fat Scale