Those scales work by measuring the resistance across your body (much like in a circuit). Since muscle conducts electricity and fat is more of a resistor, then it is theoretically able to calculate your fat percentage. However, as the last person stated, if you drank some water the measurement would change. This is because water is highly conductive. Therefore, you’re probably never going to get an accurate measurement with one of these scales. [/quote]
Also, even when set on athlete mode, those scales tend to grossly overestimate bodyfat. The difference between them and accurate professional methods is astounding. See link posted above-this topic’s been discussed at length.