Based on previous knowledge and the accumulated experiences about health maintenance by diet in Chinese medicine

the authors suggest the guiding thought based on Chinese medicine theory which meets modern diet habits and needs. Combined with the health maintenance idea "He Ze An（ harmony leading to peace） "of SUN Guangrong

a national Chinese medical master

the authors suggest systematic "Ba He（ eight harmonies） "guiding principle of health maintenance by diet

which includes harmony with season

harmony with region

harmony with age

harmony with gender

harmony with body and mind

harmony with habit

harmony with tendency of disease and harmony with nutrition. This guiding principle is essentially a harmonious system

during which the human is an integral part of nature and could fit the season

the environment

the body and mind as well as the society. This guiding principle could direct contemporary practice of health maintenance by diet more comprehensively and more systematically.