I once crossed the valley for five days. At that time, my stomach was hot and bloated because of the heavy tongue coating. So I bought dates, walnuts and vats of Nongfu Spring according to what I said on the Internet. Eat only one jujube and one walnut per meal. Those days, I was preparing for the postgraduate entrance examination and the second interview. I go to the classroom to read early every morning, and I don't feel tired after sitting all day. I was hungry before going to bed at night, but I was not hungry when I woke up the next morning. I can hear my heartbeat when I climb the stairs every day. I guess I'm short of sugar. In the next few days, there was no impulsive desire, no sexual desire, and peace of mind. The body is light. Food expenses are saved a lot. There is a saying that "people feed evil things into their bodies when they eat, and they disappear when they don't eat." I really felt this way at that time. After two or three days, the tongue coating disappeared completely, which was amazing (but after eating for a while, the tongue coating came back). On the fourth and fifth day, I was still in good spirits. After that, I have a new understanding of the limits of human beings. When I hear that someone can live without food for a month or even months, I don't think it's bragging. Moreover, for example, if I am trapped somewhere waiting for help, as long as there is water, I know I can live forever.