A bioelectrical impedance analysis (BIA) scale is a device that measures body fat. It does this by sending a low-level electrical current through the body and measuring the resistance to the current. Since fat has a higher resistance to electricity than muscle, the scale can estimate the percentage of body fat based on the resistance measurement.
BIA scales are a convenient and relatively inexpensive way to measure body fat. They are also portable, so they can be used at home or on the go. BIA scales have been shown to be accurate in estimating body fat percentage in adults, however their accuracy may be less precise in children and the elderly.