The method for determining body impedance is based on the conduction of an applied electrical current in the organism. In biological structures, application of a constant low-level alternating current results in an impedance to the spread of the current that is frequency dependent. The living organism contains intra- and extracellular fluids that behave as electrical conductors and cell membranes that act as electrical condensers and are regarded as imperfect reactive elements. At low frequencies (-1 kHz) the current mainly passes through the extracellular fluids, whereas at higher frequencies (50-800 kHz), it penetrates the intra- and extracellular fluids. Thus body fluids and electrolytes are responsible for electrical conductance, which is the inverse of resistance, and cell membranes are involved in capacitance.