In clinical practice diarrhea is called diarrhea. Generally patients with mild diarrhea will not affect calorie absorption, but if the diarrhea is more severe, it may affect calorie absorption. Usually most of the nutrients and calories from the patient’s intake of substances are absorbed and transferred by the small intestine in the human intestine. The small intestine is an absorber of nutrients that absorbs energy and converts it into calories, and when certain factors affect intestinal activity, it may affect small intestinal absorption. Diarrhea is mainly caused by intestinal infections or improper diet. When diarrhea is mild, the body’s immune system works to reduce intestinal stimulation, which in turn may not affect the absorption of energy in the small intestine. However, if the degree of diarrhea is more severe, it leads to gastrointestinal dysfunction, which affects the functioning of the small intestine. Therefore, if a patient has prolonged diarrhea, it can lead to malnutrition, and he or she may feel cold and even experience dizziness and weakness due to abnormal calorie absorption. Therefore, when diarrhea symptoms are mild, it is important to adjust the diet, keep warm and pay attention to hand hygiene to avoid the disease from the mouth, while in severe cases, seek medical attention and take intestinal medication as prescribed by the doctor.