Body fat is usually defined as the amount of fat in the body, including subcutaneous fat content and visceral fat content. Since visceral fat content is not easy to detect, fat accumulation can usually be determined by measuring the thickness of subcutaneous fat. The measurement of body fat includes whole body fat measurement and subcutaneous fat measurement, and the main measurement methods are as follows: i. Whole body fat measurement: The distribution of body fat and the amount of fat can be determined directly or indirectly by using fat-soluble radionuclides, such as krypton-85 and potassium-42. In addition, neutron activity method, two-photon method, CT and MRI can also be used to determine the content of body fat. CT and MRI are more accurate methods for diagnosing visceral obesity. The method is to scan the visceral fat area along the umbilical pore or the level of the 4th/5th lumbar intervertebral vertebrae, and the area ≥ 120m2 is over the standard. Second, subcutaneous fat measurement: 1, skin crease caliper: skin crease caliper can be used to measure the thickness of sebum outside the deltoid muscle and under the scapular angle. Add up the measurement results of two places, if it is adult male ≥4cm or adult female ≥5cm, it can be diagnosed as obese; 2, X-ray: the thickness of subcutaneous fat can be estimated through X-ray examination; 3, finger pinching method: it can be used to initially judge the nutritional status, and can also be used for the initial diagnosis of obesity disease. The method is to use the left thumb and index finger or other fingers together to pinch the skin and subcutaneous tissue that needs to be measured into folds, so that the folds are parallel to the longitudinal axis of the body, and then use calipers or skin thickness measuring instrument to measure the thickness of the root of the folds. Repeat more than 3 times to obtain 3 values and just take the average value. If the average value is >1cm, it can be called excessive subcutaneous fat. If the weight is also more than 20% of normal weight, it can be diagnosed as obesity. If the skin thickness between the two fingers pinched up > 5cm, can be initially judged to have the possibility of obesity; 4, fat percentage (F%) and body fat measurement: F% = (4.750 / body density – 4.142) × 100%; body fat = (4.95 / body density – 4.5) × 100%. The formula for calculating body density is male: 1.0913-0.0016 x (upper arm sebum + scapular sebum); female: 1.0897-0.001 33 x (upper arm sebum + scapular sebum). Usually, obesity is diagnosed if the body fat content is greater than 25% in men or greater than 30% in women. Depending on the degree, it is divided into mild obesity, i.e. weight over 20% and F% over 30%; moderate obesity, i.e. weight over 30%-50% and F% over 35%-45%; and severe obesity, i.e. weight over 50% and F% over 45%. In addition, it is worth noting that the strength should be moderate when using the finger pinch method of measurement and should not be too large or too small. The pressure applied during measurement should be kept at 10g/cm. If the pressure is too small it may affect the accuracy of the measurement, and if the pressure is too large it may cause a painful sensation.