In fact, it has been used in research since 1940. In essence, the concept of bioelectrical impedance is used to describe the measurement of electrical current changes across limbs, organs and other body sites. We routinely hear people refer to their weight and their desire to lose weight. Unfortunately, this is a very unspecific goal. A more appropriate goal would usually be to lose fat.
Body weight consists of other components besides fat.
These include muscle tissue, bone weight, and water primarily. Clearly losing weight in your bones would not be a healthy goal. We are all familiar with osteoporosis and the need to sustain thick strong bones, so we are probably in agreement that this is not the type of weight we would like to lose. In fact, we find that health suffers not so much from too much weight, but from too much body fat and too little muscle. As such, it is much more important to know the amount of muscle mass you have rather than to solely focus on your weight.