The method used in body fat weighing belongs to "bioelectrical impedance method". Lean meat and fat have different water content and different resistance. By measuring the resistivity between electrodes, the approximate data of human body composition can be calculated.
Because muscle contains more water such as blood, it can conduct electricity, but fat can't. Because the channel conductor of current in the body is muscle, the weight of muscle can be known from the difficulty of current passing, so it can be judged that people with less muscle have a higher proportion of fat.
2. Interpretation of measurement accuracy:
The data measured by the body fat scale is not necessarily accurate, and the measurement results are for reference only.
Because human body composition is calculated by resistance measurement, the hydration degree of human body will also affect the accuracy of the test. For the same person, the measured results may be very different before and after light exercise.
Skin temperature will also affect the resistance value, so the test room of the laboratory is generally constant temperature. Similarly, the environmental humidity will also affect the test results, and it is also required to keep the humidity in the test room moderate.
There are enough instruments with electrodes, accurate electrode paste position, enough calculation data and professional operators. These hardware are not available in general gyms, and the measured results are definitely inaccurate.
Extended data:
There are many methods to measure human body composition, especially human body fat, mainly including underwater weighing method, skinfold anthropometry, bioelectrical impedance analysis (BIA) and so on.
In addition, there are dual-energy X-ray absorption (DEXA), computed tomography (CT) and magnetic resonance imaging (MRI), which have developed rapidly in recent years.
However, these methods need expensive equipment and professional training, and patients are vulnerable to radiation, so they are not suitable for home use. BIA method is convenient to use, accurate in measurement results and relatively low in price, which is favored by consumers.
Baidu encyclopedia-body fat scale
People's Network-Don't be superstitious about measuring three values with three body fat scales
People's Network-Body Fat Scale may have inaccurate test data, which is for reference only.