Bioeletrical Impedance Analysis (BIA) estimates body composition via the use of small, harmless electrical currents that pass through tissues and determine density. Body fat, skin, muscle and bone contain different amounts of water and therefore possess different densities. Although these devices are popularly used in gyms and health clinics and are available in many home scales, research shows that they are extremely poor in accurately measuring body fat levels.
The more fat the individual has, the less accurate BIA becomes. And hydration status can return vastly different results measurement to measurement. It’s one thing if BIA was consistently inaccurate. At least then you could then obtain a baseline for future measurement. They are inconsistently inaccurate and that makes them completely useless. As a researcher, I tried to implement BIA devices in my clinical trials on a number of occasions but none of them were consistent or as accurate as a decent skilled skin-fold caliper technician.