1. provides heat for human body. Fat is oxidized in the human body, turning into carbon dioxide and water, releasing heat. Fat produces about 2.2 times as much calories as the equivalent protein or carbohydrate. This shows that fat is an important source of heat in the body.

2. Functions of body tissues and bioactive substances. Fat is one of the important components of human cells, especially brain nerve, liver, kidney and other important organs contain a lot of fat. Fat also constitutes body tissues and bioactive substances in the body, such as the main components of cell membranes, forming phospholipids, glycolipids and so on.

3. Function of regulating physiological function. Because fat is not a good heat conductor, subcutaneous adipose tissue is an isolation layer to protect the body and prevent body temperature from escaping. So fat has the function of keeping body temperature. Fat can also store "fuel" for the body as a backup. After eating fat, the inexhaustible part can exist in the body and be reused when the body needs calories. In addition, fat can also protect internal organs, moisturize skin and prevent earthquakes.

4. The role of dissolved nutrients. Some vitamins that are insoluble in water but only soluble in lipids can be absorbed and utilized by the human body only in the presence of fat.