The Tanita UM080 relies on BIA and is based on a person's height, weight and the strength and speed at which a safe, low-level electrical signal passes through the muscle and fat in the body. Tanita's BIA method is an all-in-one process that is accurate, convenient and fast. An electrode built into a patented foot-pad sends a safe signal through the body, and your weight, body fat, and water percentage are calculated in less than 30 seconds.