This is a way to keep fit and lose weight. Bigu means not eating whole grains, but absorbing the natural gas to achieve the purpose of losing weight and fitness. This method was first popular in the pre-Qin period. The principle of Bigu is to eliminate toxins in the body, ensure good health, and treat and prevent hypertension. Many people will have a wrong understanding of crossing the valley, thinking that crossing the valley for health is not eating or drinking. In fact, this is a misunderstanding of Guogu.