How is it measured?
The Hobart Naturopath clinic utilises the Bioelectrical Impedance Analysis (BIA) method to measure body fat composition.
The physical principle behind the BIA technique is that the body’s lean compartment, comprising approximately 60-75% electrolytic water, conducts electricity far better than the body’s fat compartment, which is very low in body water content (between 5-10%). These two compartments have, therefore, very different impedance (or resistance) values to a high-frequency electrical signal. The signal impedance measurement reflects the degree of resistance to the flow of current in the body, water being a good conductor but fat a bad conductor.
So, this technique is essentially an index of total body water, from which fat-free mass is estimated.
What is the procedure for the BIA?
You will remove any metallic objects that you may be wearing. You will remove your shoes and socks only. You will stand on the test scales while a battery-generated signal is passed through the body and an impedance value is produced.
This value, together with other details of age, height, weight, and gender are used to analyse the data and within 20 seconds produces a comprehensive personal body composition statistical analysis.
Measurement under the changing conditions of temperature and total body water distribution or blood flow volume of extremities due to exercising, taking a bath, etc., affects the measurement result since the electric resistance in the body also changes.
Therefore, it is recommended to conduct the analysis under the following conditions:
- 3 hours have passed after getting up and normal lifestyle activities are carried out during this period.
- 3 hours or more have passed after eating. (For 2 – 3 hours after eating, the impedance has a tendency to decrease.)
- 12 hours or more have passed sinc vigorous exercise. (The tendency toward changes in impedance is not stable depending on the type and rigorousness of the exercise.)
- If possible urinate before taking measurement.
- For repeated measurements, measure at the same hour if possible.
- The analysis is not accurate during the menstrual period
- Alcohol not be taken 12 hours before the test