Bigu means not eating whole grains. It is a systematic health-preserving method to lose weight, detoxify and preserve health by absorbing the essence of nature. This practice originated in the pre-Qin period and was popular among the people in China during the Tang Dynasty. Now it is also sought after by many people in South China and Japan. There are methods such as fasting abroad, all of which come from the concept of breaking the valley.

After the establishment of Taoism, many people inherited this technology and practiced the valley. According to the legend of Emperor Wu of the Han Dynasty, Wang Zhen, an alchemist in the Eastern Han Dynasty, "broke for more than 200 years (the mistake of" Japan "-the note of the leader), beautiful meat, Xu Xing and horses, and several people at the same time." The Biography of Fang Shu in the Later Han Dynasty said: "(Hao) Meng can save energy for five to ten years, including jujube pits and not eating." Cao Zhi's Argument on Daoism tells the story of Li Jian's kindness to avoid the valley, saying that he tried to "bow to sleep" and "walk comfortably without leaving the valley for a hundred days". Among the alchemists attracted by Cao Cao, Zuo Ci, Feng Junda and Lu all have divination. Ge Hong, a Taoist priest in the Eastern Jin Dynasty, opposes the idea that one-way crossing the valley can lead to immortality (he advocates that the good people who choose magic should be Xi Zhi, especially the elixir). He believes that one-way crossing the valley can lead to immortality, which is the "one-family bias" of practitioners, but he does not doubt the fitness and longevity effect of crossing the valley.

He said in "Bao Puzi Miscellaneous Answer": "The rest, there are many people who have broken the valley in three years and two years, and they are all light and good." And give concrete examples to prove that Shi Chun, a Taoist priest in the Three Kingdoms, often didn't eat for a month or a hundred days when he was treating people with qi, but Emperor Wu became suspicious when he heard about it. "This is called taking medicine and keeping it." In spring, only three or two liters of water are needed. More than a year has passed, and the color of spring is fresher and the intensity is still the same. ""There are abundant, but submit to humiliation, broken valley for three years. Watching him climb the mountain, he worked tirelessly all day. "According to" Wei Shi Lao Zhi ",Kouqian, a Taoist priest of the Northern Wei Dynasty, gave him a formula to lead the valley under the pretext of Laojun, and more than a dozen disciples got it. The Taoist king of Donglai lived in seclusion in Hanshan and was isolated from the world for more than 40 years. " Seven Zheng Yun has been published for five years, and Sun Youyue's face is light, moist and free from vulgarity after eating Guxian Pills in 1967. According to "The Biography of Southern History and Seclusion", Deng Yu, a Taoist priest in Nanyue, "has broken the valley for more than 30 years, only serving mica tablets with water and reciting the Great Cave Sutra day and night. Tao Hongjing is a good guide to the valley. "