1. Supplementary nutrition: the role of diet in nourishing viscera, qi and blood, meridians, limbs, muscles, bones, fur and nine orifices. The nutrients needed by the human body must be continuously supplemented through diet. The nutritional effect of food on human body is also manifested in the selectivity of various foods to human organs, meridians and parts.

2. Material basis of "spirit": Diet is the nutritional basis of essence, qi and spirit. Only when the body is well nourished, the essence will be sufficient and the mind will be healthy.

3. Disease prevention: Huangdi Neijing pointed out: "Righteousness exists inside, and evil can't be done", indicating that the human body is full of righteousness, and evil can't invade and make people sick. To be healthy and energetic, it is necessary to arrange diet reasonably, so as to ensure the nutrients needed by the body and the functions of the five internal organs can be vigorous. Modern medicine has proved that if the human body lacks certain food ingredients, it will lead to diseases, such as rickets caused by calcium deficiency, night blindness, beriberi, stomatitis, scurvy and rickets caused by vitamin deficiency.

4. Treating diseases: Diet therapy is often more effective than drug therapy. There are many foods that can be used to treat diseases, such as pig bone marrow for strengthening brain and improving intelligence, hawthorn for resolving stagnation, garlic for treating dysentery, angelica mutton soup for treating postpartum blood deficiency, and adzuki bean for treating edema.

5. Anti-aging and anti-aging: For the elderly, we must pay attention to the deployment and maintenance of diet. Only in this way can we delay aging. The reason why diet is anti-aging and anti-aging is that its function is produced by tonifying kidney and benefiting qi, nourishing kidney and strengthening body. Deficiency of kidney essence can lead to signs of premature aging such as loose teeth, premature whitening and forgetfulness.