Body fat rate refers to the proportion of human fat in various tissues of the body, or the percentage of total weight. Besides body mass index (BMI), it is another reference to measure obesity (excess fat) or emaciation (lower than healthy body fat). It is also the main reference to observe the relationship between fat content and disease prevalence or mortality by epidemiological methods. There are many ways to determine the percentage of body fat, and the following are commonly used at present:
1. Formula calculation: body fat rate = [body fat weight (㎏)? Weight (㎏)]? 100%。
Body fat weight (female) = [waist circumference ()? 0.74]-[ Weight (㎏)? 0.082+34.89]。
Body fat weight (female) = [waist circumference ()? 0.74]-[ Weight (㎏)? 0.082+44.74]。
This formula is suitable for people with relatively symmetrical figure, so there will be some errors.
2. Body fat scale: Body fat scale is a common method to detect body fat rate in fitness and weight loss institutions and families. In fact, the body fat scale measures its body fat rate by bioelectrical impedance method and the resistance difference between the fat part and the non-fat part. In fact, this method is not accurate, and the measurement will be affected by external temperature and humidity.
Image detection: It is a method of measuring body fat area by using computed tomography and magnetic resonance imaging, which can accurately determine the percentage of body fat, but these instruments and equipment are expensive and only used for laboratory research.
Contribution of fat to human body
First, essential fatty acids are the main components of human tissues and cells, especially for the structure of mitochondrial membrane and cell membrane. The transport and metabolism of cholesterol in the body are also inseparable from essential fatty acids. Essential fatty acids also have protective effects on skin damage caused by X-rays.
Secondly, prostaglandin is also synthesized from fatty acids, which are the main regulators to maintain cardiovascular system, protect gastrointestinal tract and stimulate uterine smooth muscle contraction. Leukotrienes and w-3 fatty acids play a key role in leukocyte aggregation, vascular permeability, brain and visual development, respiratory system and coronary artery.
Thirdly, phospholipid is an important component of biofilm and an important raw material of plasma lipoprotein. Nerve tissue contains a lot of phospholipids. Phosphatidylinositol monophosphate is closely related to norepinephrine receptor. The activities of many enzymes on the membrane are also inseparable from phospholipids.
Fourthly, the absorption of fat-soluble vitamins and carotene depends largely on fat. At the same time, it plays a vital role in maintaining a constant body temperature and resisting cold.
What should be a healthy body fat rate?
According to the standard recommended by Dietary Guidelines for China Residents (20 16), the healthy body fat range of adults in China should be kept at 15%~20% for men and 25%~30% for women. For the needs of health and physiological function, the essential body fat for men should be at least 3%~8%, and for women it should be at least 12%~ 14%.