The Mawangdui silk manuscript Quegu shiqi

Among the silk manuscripts excavated in 1973 from Han tomb no. 3 at Mawangdui in Changsha, Hunan, is a short text that its editors named Quegu shiqi, “Abstaining from Grain and Eating Qi”, one of the earliest surviving texts devoted to bigu and to shiqi (breathing and guiding exercises) (湖南省博物馆、复旦大学出土文献与古文字研究中心 编纂 2014).

Reading: One who abstains from grain eats shiwei instead.

The manuscript is badly damaged; the legible parts describe replacing grain with shiwei (a fern), increasing and decreasing it with the phases of the moon, and combining this with breathing methods that change with the seasons. Two points are worth noting. First, “abstaining from grain” does not mean eating nothing: the text specifies a substitute food. Second, it is a text of cultivation techniques, not a record of observations on nutrition or disease.

Ge Hong’s criticism

The Baopuzi neipian of Ge Hong of the Eastern Jin is an important work of Daoist cultivation literature. Ge Hong himself believed that immortality could be learned, yet he took a notably sober view of “cutting off grain”.

Reading: Although Daoist books say that one who wants long life must keep the intestines clear, and one who wants to escape death must have no residue in the intestines; and also that grass-eaters run well but are dull, meat-eaters are strong but fierce, grain-eaters are clever but short-lived, and qi-eaters are spirit-bright and do not die, this is only the one-sided teaching of a single school of qi-circulators and cannot be relied on alone. … Cutting off grain can only save the cost of food; it cannot by itself make a person live long.

This is a rare piece of “internal criticism”: a Daoist scholar states plainly that sayings such as “no residue in the intestines” are one school’s bias, and that cutting off grain cannot by itself bring long life. In the same chapter he also records reports of grain-abstainers who were “light in body and of good complexion”, and discusses substitute foods and drugs used during abstention, showing that “cutting off grain” in his time was mostly not complete fasting.

The Huangdi Neijing: nourishment by food, and “cutting off grain”

Reading: The five grains nourish, the five fruits assist, the five domestic animals benefit and the five vegetables supplement; taken together with their flavours in harmony, they replenish essence and boost qi. When treating illness with strongly toxic drugs, stop when six-tenths of the illness is gone; with ordinary toxic drugs, at seven-tenths; with mildly toxic drugs, at eight-tenths; with non-toxic drugs, at nine-tenths; grain, meat, fruit and vegetables then nourish the patient to finish the cure; do not overdo it, lest the upright qi be harmed.

The sentence “grain, meat, fruit and vegetables nourish to the end; do not overdo it” is often read as “eat moderately, do not overeat”. In context, the sentence concerns the principles of using drugs in treatment: stop the drugs at a certain point and leave the rest to nourishment by food. “Do not overdo it” most naturally refers to not overdoing treatment and harming the upright qi, though some translators apply it to food as well; either way the passage concerns convalescence, not a rule about restricting food.

A passage in the Lingshu states the consequence of cutting off food and drink altogether:

Reading: A healthy person who neither eats nor drinks for seven days dies, because the essential qi and fluids made from food and water are all used up.

This speaks of “neither eating nor drinking”, going without water as well, which differs from going without food alone, and the figure of seven days should not be taken as a precise physiological judgement. But it shows clearly that ancient physicians did not regard cutting off all food and drink as safe.

The Analects: restraint, not abstinence

Reading: He did not object to his grain being finely pounded, nor his minced meat finely cut. … However much meat there was, he did not let it exceed the staple food. Only in wine he set no fixed limit, but never to the point of disorder. … He did not remove the ginger from the table, and did not eat much.

“He did not object to finely pounded grain” is often misread as “Confucius insisted on refined food”. The more widely accepted reading is that the passage records Confucius’ particular care and restraint in eating: no spoiled food, meat not exceeding the staple, wine never to the point of disorder. “Did not eat much” has long had different readings: some take it to refer to the ginger alone, others to eating in general. Either way, “Xiang Dang” describes a restrained everyday diet, not fasting.

Reading together: two traditions to keep apart

Taken together, these texts show at least two strands in the classical tradition:

• One is nourishment by food and restraint: grains as the basis of nourishment, combined as needed, without excess or gorging. It has something in common with modern nutrition’s moderate calorie restriction, regular meals and time-restricted eating (in people for whom it is medically safe).
• The other is abstaining from grain and eating qi as cultivation techniques: replacing grain with substitute foods and breathing methods, aiming at long life or immortality. Even within Daoism, Ge Hong called this “the one-sided teaching of a single school” that “cannot by itself make a person live long”.

Today’s marketing of bigu often dresses the second strand up as the first, or dresses both up as an “autophagy therapy” already proven by modern science. The earlier chapters have shown that there is no human evidence that “so many days of fasting clear away so much disease”; prolonged complete fasting breaks down muscle and organ protein and disturbs electrolytes, and can be fatal in severe cases; and for the people listed at the start of this book, even short fasts can be dangerous.

Summary

The Mawangdui Quegu shiqi describes a technique of replacing grain with shiwei combined with breathing; Ge Hong explicitly criticised “no residue in the intestines” as one school’s bias and said that cutting off grain cannot by itself bring long life; the Suwen’s “grain, meat, fruit and vegetables nourish to the end” concerns nourishment by food in the later stage of treatment; the Lingshu says that one who neither eats nor drinks dies in seven days; and the Analects describes a restrained diet. The idea of restraint in the classical tradition deserves respect, but it does not support life-threatening extreme fasting and is no evidence for any modern health claim. The next chapter returns to practice: a checklist for a personal log, and a pre-registered trial that can test early time-restricted eating.