The Yellow Emperor’s Classic of Internal Medicine points out that “the ancient people, who knew the law of yin and yang, and in the arts and figures, eating and drinking in moderation, living in a regular manner, not delusional labor, so that the form and the spirit, and the end of its natural life, a hundred years before leaving.” The ancient people mentioned in the book mainly refer to people with wisdom in long ago, from which some clues of scientific diet can be found. During the Paleolithic period, 65% of the energy obtained by humans came from fruits and vegetables, about 25% from grains, and about 10% from animal food. During the Neolithic period, as the reliance on grains increased, the energy supply from fruits and vegetables decreased to about 40%, grains supplied more than 50% of the calories, and the proportion of meat decreased. The Shennong Ben Cao Jing recorded 59 kinds of food, of which 48 were plant-based, reflecting from the side that plant foods dominated the diet. The diet structure began to change during the industrialization period, and the use of grain refining equipment reduced the fiber content of cereal foods. New vegetable oil extraction processes increased their consumption. The availability of poultry, livestock, and other raised meat increased dramatically. Innovations in transportation equipment have facilitated the delivery of salt and sugar, and the application of salt and sugar has increased dramatically. In contemporary times, commercialized finished foods have proliferated and additives in foods have increased. High calorie, high fat, high salt, low fiber and low micronutrients are the characteristics of today’s food structure. Obesity, poor motor system development, endocrine disorders, and increased mental and psychological stress have become common phenomena in society. In general, the human diet has changed roughly: from a fruit- and stem- and leaf-based diet supplemented by cereals and meat; to a cereal-based diet supplemented by fruits, stems and leaves and meat, and finally to a contemporary high-protein, high-fat and high-calorie diet. The Yellow Emperor’s Classic of Internal Medicine says: “Man is born with the qi of heaven and earth, and the law of the four seasons.” Like everything else in the universe, human beings are born from the qi of heaven and earth and grow according to the laws of the four seasons. Paying attention to every detail of the diet and adapting to nature is the way for human beings to survive. A diet based on a variety of plants, seeds, nuts, vegetables and fruits, supported by milk, eggs, fish and lean meat, is more suitable for the natural evolutionary characteristics of human beings. Plant calorie intake is recommended to account for 70% of total calorie intake. Since plant calories are low and animal calories are high, grains and cereals, vegetables and fruits should account for more than 90% of the total diet. The Yellow Emperor’s Classic of Internal Medicine points out that “five grains are nourishing, five fruits are helpful, five animals are beneficial, five vegetables are filling, and the odor is taken in harmony to nourish the essence and benefit the qi”, that is, cereals are taken as the main food, fruits are supplemented, meat is taken as a side dish, and vegetables are used to supplement nutrition. These contents are undoubtedly the crystallization of the wisdom of Chinese nutrition, and still have far-reaching guiding value today.