Traditional Korean medicine has a theory of "heaven and man unite", that is, the small environment in the human body must be harmonized with the large environment in the natural world in order to make people more compliant with changes in the natural world and increase the human body's resistance to adverse external influences. According to this theory, in the hot summer days, Koreans are more inclined to eat:. ['old food to reduce the temperature of the human body and adapt to the needs of the external environment.', 'hot food, supplement the calories and nutrients lost by the body due to heavy perspiration in a "hot supplement" manner.', 'a reasonable mix of cold and hot foods to maintain balanced body temperature and nutrition.', 'food that is neither cold nor hot, to avoid the excessive temperature difference between the human body and the external environment and loss of nutrients.']