How does bioelectrical impedance analysis indicate body composition?
Bioelectrical impedance analysis is now widely used in the medical field to distinguish the amount of body water, body fat and skeletal muscle in a body.
The analysis first obtains total body water (TBW). This is the amount of fluid that can be found inside and outside your body cells. For an adult, total body water represents 45 to 60% of total body weight.
The other components—with more insulating properties such as body fat or skin—will be more “resistant,” meaning that they conduct electricity less effectively.
Using ratios of bioelectrical impedance measured at a separate frequency, complex equations then estimate the amount of fat-free mass within the body. The amount of body fat is finally deducted from the total weight.
Beyond body composition
Note: Bioelectrical impedance is also a method used in cardiology to assess pulse wave velocity, another biomarker that determines the stiffness of the arteries to infer cardiovascular health.
Learn more about pulse wave velocity.