The measurement of body components is central to the study of body composition in animals and humans. The principle underlying the use of bioimpedance analysis (BIA) for assessing body composition is the relationship between body composition and the water content of the body. Resistance and reactance, the two main determinants of impedance, respond differently at any given frequency to intra-cellular and extra-cellular fluids. Estimation of fat and fat free mass is discussed. Footpad Vs lying position in term of measurement approach as well as accuracy are presented.Using BIA we can measure water content of the body at population level and using specific and appropriate equations we will have the possibility of detecting subjects at risk of overweight and obesity
