Fat rate can be measured by special health scale or other methods. Judging from the current measurement technology, the biological resistance method is mainly used. The principle is that muscle contains more water such as blood, which can conduct electricity, while fat can't. Therefore, the resistance can be calculated by the small current flowing through the body, and the fat rate can be measured from this.
The following are several international fat content measurement methods:
1. Underwater weighing method (underwater weighing)
It is a method to calculate the weight of body fat by measuring the water displacement, lean body mass density and adipose tissue density of human body, and then calculate the percentage of body fat content. This method has small error and high precision, but it needs special test space and tools and has many operation steps. It is only suitable for laboratory testing and not suitable for public self-testing. The principle of underwater weighing method is also very simple: the specific gravity of human body fat is about 0.8 kg/L, and the average specific gravity of other tissues except fat is about1.0 kg/L. By weighing the weight of human body in air, the weight when it is filled with air in water and the weight after it is exhausted in water, the total weight of human body fat can be obtained by simple calculation.
2. Sebum forceps measuring caliper (anthropometry-skin wrinkle measurement)
It is a method to calculate the percentage of body fat by measuring the thickness of subcutaneous fat at multiple points. This method is closely related to the human model used in the calculation process. The data of European and American mannequins can't be used in Asia, and Japanese models can't calculate the data of China people well. This method has been widely used in many countries in recent decades because of its simple operation and almost no need for space.
3. Dual energy X-ray absorption method (DEXA).
It is a method to measure the body fat content by using the principle that different tissues (minerals, lean meat and fat) have different absorption rates of X-rays. In the test, two low radiation sources detect synchronously in small steps. This method is a relatively new method with high accuracy, but the test cost is expensive and the test time is long (10-20 minutes/person). Can only be used in advanced laboratories, not outside the experiment.
4. Near-infrared interaction
It is a method to measure the fat content of human body by using the principle that near infrared rays have different degrees of penetration and reflection on different tissues of human body. The measurement of biceps brachii is often used as the main test site, and the percentage of body fat content can be calculated by substituting the test data into the equation including height, weight, body shape and activity level. This method has been widely used outside the laboratory because of its cheap instruments and simple measurement steps. However, because the pressure of the probe on the body tissue is different every time, the measurement data of the same subject are often different, so the test accuracy of this method is poor.
5. Magnetic resonance imaging (MRI)
Based on X-ray, it is a method to measure the fat content of human body by using the characteristics that human tissue cells are "excited" in different degrees under the action of magnetic field. A measurement takes about 30 minutes, and the measuring equipment is expensive. Although the measurement accuracy is high, this method is only suitable for advanced laboratories.
6. Total Body Conductivity (Tobec) for thin body conductivity measurement.
It is a method to measure lean body weight, and its principle is that human (non-fat) lean body is a good conductor. Although this method has high accuracy, the test time is only 10 second, but the application scope is limited to advanced laboratories because of the expensive test instruments.
7. Computed tomography [X-ray].
The X-ray tube in CT produces a beam of X-rays around the human body, which is received by the probe and generates the cross-sectional information of the human body. The computer uses complex algorithms to construct the tissue image in the human body. The equipment of this method is expensive, and the human body is exposed to radiation, so this method is limited to laboratory application.
8. Exhaust measurement method BOD POD (exhaust volume)
The measuring principle of this method is similar to the underwater weighing method. It is a method to calculate the body density by using the volume of air discharged from human body, and then calculate the fat content and ratio. During the 20 seconds required for the test, the tester sits in a sealed cabin, and the amount of air discharged is measured by a sensor connected to a computer. This method requires expensive equipment and is not convenient to carry out outside the laboratory.
9. Bioresistance measurement method BIA (bioelectrical impedance)
It uses the characteristics that thin tissue of human body is a good conductor and fat is an insulator, discharges current to human body through different electrodes, then measures human body resistance, and then substitutes the test results into the equation including height, weight, sex and age to calculate the fat content and proportion of human body.
Fat rate and weight loss
Obesity/overweight
We often say, "I've gained weight recently, and I've gained three or four pounds." Because weight can reflect our fatness and thinness, and it is very convenient to measure, we often use it to measure fatness.
In fact, this concept is not desirable-weight is affected by many factors, such as physical condition, bone size, muscle proportion, water content and so on. These will affect the weight, but they can't accurately reflect the fat and thin figure.
So we say that it is unscientific to take weight as the only indicator to measure obesity.
lose weight
When we lose weight, weighing scale is often what we miss most every day-any slight change in the pointer has become the weather vane of our daily mood.
However, because weight is influenced by many factors, taking weight loss as the purpose of weight loss often leads to great deviation in our weight loss-the vacillation of weight affects our confidence and determination to lose weight; The simple pursuit of weight loss leads us to adopt the method of fast weight loss, and most of these methods are to reduce muscle and water, so our weight loss is easy to rebound.
So don't rely so much on your weighing scale pointer, sometimes it will cheat you!
So, how do we know whether we are fat or thin, and how do we test our weight loss effect?
Obesity = high fat rate
The purpose of losing weight is to finally have a beautiful body and a healthy body. Every action during our weight loss is to achieve this goal.
Judging from the body composition, our body is mainly composed of several parts-bones, internal organs, lean muscle tissue (hereinafter referred to as muscle), water and fat. Obviously, the first two parts are basically fixed; Muscle is the main place to consume calories, and its reduction will lead to the decline of metabolism, so you can't lose weight by losing muscle; The water content will change, and it will be easily excreted and replenished; Moreover, fat not only has a great influence on our appearance, but also does great harm to our health, so the fundamental goal of losing weight is to lose fat!
Obesity does not simply mean overweight, but refers to abnormal or excessive fat accumulation. To measure whether you are obese, you can measure the proportion of adipose tissue in your body, that is, the fat rate.
Lose weight = lose fat
When we lose weight, taking the fat rate as another indicator can better reflect our weight loss effect and whether the direction of weight loss is correct.
What you must remember is that every action you take to lose weight is to lose weight, not to lose weight. Therefore, some behaviors, such as reducing water or muscle tissue (muscle is the main place to consume calories, and reducing muscle in weight loss is equivalent to suicide), are contrary to our goals and even hinder us from losing weight.
Combining the obesity standards of the World Health Organization and some obesity societies in Asia, the Mint expert group made a judgment on the healthy fat rate and obesity degree suitable for China people, and thought that for adults, the fat rate exceeding the standard level means that they are more likely to suffer from various chronic diseases than ordinary people. For children or adolescents under 18 years old, this standard can not be used as their reference because fat cells are not fully mature.
How to judge that the fat rate is too high
Weight gain depends on body fat rate. The following test questions can help you figure out what fat percentage is.
1, now more than 5 kilograms heavier than 18 years old;
2, eat quickly, sweep everything on the plate;
3, the weight has not changed, but the muscles are getting more and more relaxed;
4, the mouth always keeps eating, snacks can always be found in the bag;
5, love to eat fried food;
6. The ratio of waist circumference divided by hip circumference is greater than 0.77;
7. Even from the first floor to the second floor, take the elevator;
8. You always keep losing weight and keep rebounding.
Results:
A. If the answer is yes, it means that your body fat rate is above 30%. You have accumulated excess fat in your body. If you don't take action, you will get fatter and fatter. Obesity is considered when the body fat rate exceeds 30%. Not only does it look bloated, but it is also prone to various diseases. Risk index: 8
B, 3-5 is the affirmative answer. Your body fat rate is between 25% and 30%. You don't look fat, but you are strong. This may also indicate that you are approaching obesity step by step, change your diet and living habits as soon as possible, and start exercising. Risk index: 5
C, the affirmative answer is below two: the fat rate is below 25%. Although you are still slim, keeping good diet and living habits is the best way to keep fit. Risk index: 2