Body composition analyzers generally use the multi-frequency segmental bioelectrical impedance method to measure body fat, weight, muscle mass, BMI (body mass index), non-fat mass and other health indexes, which can accurately evaluate human muscle and fat The content and proportion of body components such as water and water reflect the nutritional status of the human body, obesity, edema and other physical health conditions, effectively indicate the physical health status of the guests, and provide independent health analysis data reports for each tester. Through the body composition analyzer, testers can clearly understand the corresponding data indicators of their own body, find the track of physical condition improvement, and formulate new diet and exercise plans.
Essential fats for life: essential fats for maintaining life activities and reproductive functions. This part of fat people cannot lose weight as long as they live.
The essential fat rate for boys is between 4-5%, that is to say, there are basically no men with body fat lower than 4%, even top bodybuilders.
The essential fat rate for girls is 10-13%, that is to say, there are basically no women with body fat below 10%, even top bodybuilders. If the body fat of girls is less than 10%, symptoms such as menstrual disorders, breast shrinkage and even amenorrhea will appear.

How much body fat is there, and how does the body fat scale measure it?
A body fat scale is actually a device for measuring body composition. Body composition generally refers to the macroscopic components that make up our body, mainly in two parts: fat and lean body mass. Fat is easy to understand, it is the fat on our body, including the stored fat in internal organs. The concept of "lean body mass" is understood by many people as muscle, which is actually wrong. Lean body mass, in addition to muscle, also includes bone, a very small amount of essential fat, and some other non-fat tissue.
How does the body fat scale distinguish fat and non-fat tissue in the human body? In fact, body fat scales are based on a technique for measuring body composition called bioimpedance analysis (BIA). The principle of this technology can actually be guessed by looking at the name. Simply put, it is to distinguish fat and lean body mass by their different conductivity.
The BIA analysis method is to place several contact electrodes on the surface of the human skin and input a fixed current to obtain an electrical impedance value. Then use the formula to calculate the body composition of the human body. On the body fat scales we usually use, there are several smooth metal touch panels, which require us to step on them with bare feet or hold them with our hands. These metal contact plates are the contact electrodes.
Because the final result of BIA analysis is calculated by using the electrical impedance value through the formula, BIA is a "black box" method, and the direct result of the measurement is very simple, only one electrical impedance value, and the rest of the conclusions need to be calculated.

How to use BIA to measure body composition clinically?
BIA analysis method, although some laboratories and hospitals are also using it is simple and convenient to operate, and can be miniaturized and portable. There are so many points that must be done in laboratory BIA analysis, from equipment, operation method, to the requirements of the testees. arrive.
a. The number of electrode sheets should be sufficient. The contact electrodes of BIA equipment range from 2 to 8. Some hand-held BIA analyzers only have 2 contact electrodes. The measurement accuracy of such equipment is quite low. Generally speaking, at least 4 contact electrodes are required, and some devices use 8 contact electrodes, so that the measurement results will be more accurate.
b.  The contact electrodes must be attached to the skin surface. The advantage of sticking to the surface of the skin is that the pressure of the electrode contacting the skin can be stably controlled. Because BIA measures the electrical impedance value, the measurement results will be affected if the electrode is in contact with the skin too tightly or too loosely. The correct position can improve the accuracy of the measurement, which is also related to the thickness of the skin. The standard requirement is to be attached to the back of the hand, wrist joint, instep and ankle joint.
c. The temperature and humidity of the measurement room should be constant. Skin temperature also affects the measured electrical impedance value. If the temperature of the measurement chamber is too high or too low, it will affect the skin temperature of the person being tested. The skin temperature is high, and the measurement results tend to make the body fat rate low. The skin temperature is lower, and the measurement results, body fat percentage tend to be higher. Where the electrode contacts the skin, the humidity of the skin also has certain requirements, and the skin is generally required to be moist. If the test environment is too dry, it will affect the test results.
d.The palms are prone to sweating, some people sweat a lot, and the skin contacting the electrodes is too wet, which will interfere with the measurement results of the electrical impedance value. Similarly, the indoor temperature and humidity are not constant, which will also affect the measurement results. The air in the north is very dry in winter, and the measured electrical impedance value of dry skin is completely different from that of normal moist skin.