Dietary nutrition is one of the important factors that affect people's healthy life. Insufficient nutrition and unbalanced nutrition are the important causes of many diseases, such as diabetes, hypertension, coronary heart disease, hyperlipidemia, gout, cancer and so on. These are all related to unbalanced diet. There are more than 50 kinds of nutrients needed by human body, which can be divided into seven categories, namely: protein, fat, carbohydrates, minerals (including trace elements and macro elements), vitamins, dietary fiber and water. Among them, protein, fat and carbohydrates can generate heat during metabolism, so they are collectively called "three thermogenic nutrients". These seven nutrients not only have their own special functions and complete their respective tasks, but also constitute a reasonable and scientific basic nutrition system. They coordinate and cooperate in the whole process of nutrition, fulfilling the sacred mission of regulating human life and physiological activities. A balanced diet consists of various foods in a reasonable proportion and manner, which complement each other and provide comprehensive, balanced and moderate nutrition.

A balanced diet is a scientific and reasonable diet. The heat energy and various nutrients provided by this diet should not only be comprehensive, but also the nutritional supply of the diet must be balanced with the needs of the human body. At the same time, various nutrients can maintain an appropriate proportion, cooperate with each other without imbalance, take care of different ages, sexes, physiological conditions and special circumstances, and achieve a nutritional balance between supply and demand. China Nutrition Society has formulated dietary guidelines according to the national conditions. Its principles include: "Food should be diverse, hunger should be appropriate, oil should be appropriate, thickness should be matched, salt should be limited, sweets should be eaten less, drinking should be moderate, and three meals should be reasonable." If we can abide by these principles for a long time, we will certainly meet the requirements of reasonable nutrition.