Reasonable dietary nutrition can prevent the occurrence and development of many diseases, while unreasonable diet, overnutrition or undernutrition will bring different degrees of harm to health. Overeating will lead to obesity, diabetes, cholelithiasis, hyperlipidemia, hypertension and other diseases due to overnutrition, which will not only seriously affect health, but also shorten life expectancy. Insufficient nutrients in the diet for a long time will lead to malnutrition, anemia, lack of various elements and vitamins, which will affect children's intellectual growth and development, and the human body's disease resistance and ability to work, work and study will decline.

A reasonable diet must consist of a variety of foods in order to achieve the goal of balanced diet. And food can be divided into the following five categories according to its composition:

1. Cereals and potatoes

It mainly provides carbohydrates, protein and B vitamins, and is the main source of heat energy for China's diet, such as white rice and purple rice.

2 animal food, such as meat, poultry, eggs, fish, milk, etc.

It mainly provides protein, fat, minerals, vitamins A and B and essential fatty acids.

3. Soybean and its products

It mainly provides protein, fat, cellulose, minerals and B vitamins.

4. Vegetables and fruits

Mainly provides cellulose, minerals, vitamin C and carotene.

5. Pure heat food

Include animal and vegetable fats, various edible sugar and alcohol, which mainly provide heat energy and essential fatty acids.