The water excreted in diarrhea is partly water from the food and partly body fluids. In diarrhea, the nature of the stool is relatively thin, and in severe cases, watery stools may occur. Food enters the digestive system with a large amount of water, which is normally absorbed by the intestinal system and enters the body’s blood circulation. However, when diarrhea occurs, the absorption function of the intestinal tract is affected, so it is not able to absorb the water in the food, resulting in the excretion of the water in the food in its original form, so there is more water in diarrhea. When diarrhea occurs, the body will be in a state of hyperosmolarity, and water in the body will seep into the intestinal system through the intestinal wall, and in severe cases, water in the blood will also seep into the intestinal system, thus causing more water in diarrhea. When watery stools occur in diarrhea, it is necessary to rehydrate the body in order to prevent dehydration.