Principles of Bioimpedance Analysis (BIA)

Bioimpedance Analysis (BIA) has been used to determine body composition since the 1970s. It involves passing a low-intensity alternating electric current through the body and measuring the opposition of the tissues to the current. The value of the impedances, phase angles, resistances and reactances collected by the measuring device make it possible, thanks to algorithms, to determine the body compartments crossed by the current and to provide, according to the type of device, a more or less precise and detailed result of the body composition. The current used is of very low intensity. It is completely painless.


The eBIODY devices are equipped with AMINOGRAM’s patented Direct Measuring Connection. This measurement socket avoids possible interference between the electrodes and a direct hand/foot connection.

Here are the differences between direct and indirect measurement devices.

Multi-frequency technology

Electrical currents have different penetration capacities depending on their frequency. Thus, the multi-frequency technology allows to measure more impedances and to bring more reliability and precision to the results obtained.

The eBIODY devices use 5 frequencies: 5, 20, 50, 100, 200 kHz


Body compartments

The multi-frequency devices allow to go a long way in the analysis of the body compartments, up to 7 compartments can be analysed.

Two methods in bioimpedance analysis

Multi-algorithm method

The two most common methods in bioimpedance analysis are the deductive Mono Algorithm approach which is based on the assumption that “whatever the individual (gender or age), their hydration is constant (e.g. at 73.3% of their Fat-free Mass) and the other compartments are defined only by coefficients based on constants, this method employs a single algorithm for water”.

The other method, the Multi Algorithm approach, includes the essential algorithms such as an algorithm for Fat Free Mass and an algorithm for total water to obtain the actual hydration level of the Fat Free Mass and thus detect whether the person is well hydrated, over hydrated or under hydrated.