How do digital scales calculate body fat?
Digital scales purport to measure your body fat through a process called BIA, or bioelectrical impedance analysis. Essentially, it clocks the speed that electricity travels through you. The scale runs a low-level electric current through your body, using your feet as positive and negative electrodes. The current encounters different levels of impedance, or resistance, from fat versus muscle. The scale measures this impedance, and throws it together with other factors (age, sex, height) to come up with your BMI, or body mass index. That’s how it works in theory, but several fitness message boards complain that BIA is unreliable at best, complete bunk at worst. A numbing trawl through several retail sites resulted in all kinds of other dubious sounding terms like “floating code thickness measuring system” and “sophisti
