Abstract: A body composition analyzer provides the resistive and reactive components of a body's measure impedance as well as body fat information and ideal weight information. The analyzer includes an analog circuit under the control of a microprocessor for providing signals to the microprocessor that are representative of the voltage across the network formed by the body and of the voltage across a reference network of known impedance that is connected in series with the body network. The microprocessor calculates the body networks impedance as a function of the ratio of the body network voltage and reference network voltage signals to provide extremely accurate results. The body composition analyzer is a hand-held unit that can transmit data to a peripheral device for recording via a wireless communication network. The analyzer is further programmable so that various algorithms and constants stored therein can be updated.