Source:http://linkedlifedata.com/resource/umls/id/C1704746
NCI: A method to assess body composition, i.e., the relative percentages of body weight comprised of fat tissue and lean body mass. It is based on the principle that the resistance to an applied electric current is inversely related to the amount of lean body mass within the body. Impedance is greatest in fat tissue, which contains only 10-20% water, while lean body mass, which contains 70-75% water, allows the signal to pass much more easily.