Korean traditional medicine has the theory of Harmony of Man and Nature, that is, the small environment in the human body should be coordinated with the large environment of nature, so as to make people more adapt to the changes of nature and increase the resistance of the human body to the adverse effects of the outside world.
According to this theory, Lukewarm food is the food that Koreans prefer to eat in hot summer in order to avoid excessive temperature difference between the human body and external environment and nutrient loss.