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Huangdi said: I wish to hear why a person dies after seven days of not eating.

Bo Gao replied: Please allow me to explain the reason. The stomach has a capacity of one chi and five cun in circumference, a diameter of five cun, and a length of two chi and six cun. Its curved portion can hold three dou and five sheng of food and water. Typically, it retains two dou of grain and one dou and five sheng of water, at which point it is full. The Upper Jiao (Upper Burner) disperses Qi, releasing fine essences. The vigorous, swift-moving Wei Qi (Defensive Qi) flows downward to irrigate the various intestines. The small intestine has a diameter of two cun and half, plus one-eighth of a fen, and a length of three zhang and two chi. It can hold two dou and four sheng of grain and six sheng and more than half a he of water. The returning intestine (Hui Chang) has a diameter of four cun plus one-third of a cun, and a length of two zhang and one chi. It can hold one dou of grain and seven sheng and a half of water. The broad intestine (Guang Chang) has a diameter of eight cun plus two-thirds of a cun, and a length of two chi and eight cun. It can hold nine sheng and one-third of a he of grain. The total length of the gastrointestinal tract is five zhang, eight chi, and four cun, capable of holding a total of nine dou, two sheng, and more than half a he of food and water. This is the quantity of food and water that the gastrointestinal tract can contain.

However, a healthy person is different. When the stomach is full, the intestines are empty; when the intestines are full, the stomach is empty. Through this alternating cycle of fullness and emptiness, Qi circulates up and down, the Five Zang Organs remain stable, and the blood vessels are harmonious, allowing Shen (Spirit) to reside within. Therefore, Shen is the refined essence derived from food and water. Consequently, the gastrointestinal tract typically retains two dou of grain and one dou and five sheng of water. Thus, a healthy person defecates twice daily, expelling two sheng and a half each time, totaling five sheng per day. Over seven days, 5 x 7 equals 35, or three dou and five sheng, meaning all retained food and water are exhausted. Therefore, if a healthy person dies after seven days without eating or drinking, it is because the food, water, refined essence, and Jin-Ye (Body Fluids) have all been depleted.

This passage discusses how the human viscera, physical form, Shen, Qi, and Blood all rely on food and water for nourishment and generation. If food and water are cut off, both form and Qi will perish. The *Ling Shu · Chapter 6: Six Sections and Visceral Manifestations* states: "When the five flavors enter the mouth, they are stored in the gastrointestinal tract. The flavors are stored to nourish the Five Qi. When Qi is harmonious, life arises; when fluids and liquids are formed together, Shen naturally generates." Hence, Shen is the refined essence of food and water. The phrase "a healthy person is different" refers to ordinary individuals without disease, whose stomachs are full while their intestines are empty, and vice versa. They digest continuously throughout the day and night, retaining only three dou and five sheng, without such accumulation. Therefore, after seven days without eating, the retained food and water are completely expelled. Once the food and water are gone, the refined essence and body fluids are also depleted. Wang Fanghou stated: Patients who do not eat for seven days but do not die do so because of retained food and water accumulation. Generally, retention constitutes a pathological state.