About body composition monitors

It is possible to monitor body composition, injecting a small electric charge into the patient body through electrodes using the BioElectrical impedance method.
How does it work? Body fat has little electric conductivity meanwhile muscles have an higher water content and have higher conductivity. Using these simple principles some companies have made up tables corresponding to real values measured by weighing people in water, because fat has a lower specific weight than other tissues. All these tables work by measuring foot to foot, so it is possible to measure the fat in the buttocks. Other work by measuring foot to arm, so to take in consideration also the fat in the belly. Of course, to measure in this way one needs to have bare feet and there are many good devices, for example made by Tanita or Omron, that can do a very good job in your room, when you are naked.
Measurement of body fat in a public weighing scale is a completely different story, because customers have shoes. One could try to measure hand-to-hand, but results have nothing to do with the reliability on measuring starting from the feet because the current flows only through arms and chest, where it could cause problems to pace-maker holders or pregnant women, and cannot detect buttocks or lower belly. We manufacture BodyWeight scales since 1985 and many times we have been asked why we don't measure body-fat hand-to-hand. We have always ruled out this approach, because we want safety first for all our users and we don't think the quality of the result is worth the risk.
We prefer to use BMI, that is a reliable way to assess people obesity using the tables provided by the World Health Organization. All Body Weight people weighing machines have Body Mass Index calculation.