Fat cannot be absorbed by the small intestine, which may be caused by physiological factors such as excessive fat intake, but it cannot be ruled out that it is caused by enteritis, malabsorption syndrome, cholecystectomy, chronic pancreatitis and so on. 1. Physiological factors: overeating or consuming too much fatty food, etc. leads to excessive fat intake, which exceeds the amount digested and absorbed by the small intestine, thus leading to fat not being absorbed by the small intestine. 2. Pathologic factors: (1) enteritis: enteritis is mainly manifested as fever, nausea, diarrhea and other symptoms, which can also lead to intestinal absorption dysfunction, so that fat can not be absorbed by the small intestine. (2) malabsorption syndrome: malabsorption syndrome patients often manifested as diarrhea, fatigue, swelling, etc., if the fat absorption disorder can also lead to steatorrhea. (3) Cholecystectomy: As the bile entering the duodenum is not concentrated and processed by the gallbladder, the concentration of bile in the duodenum decreases significantly, which leads to problems in fat digestion and absorption. (4) Chronic pancreatitis: Chronic pancreatitis patients will also have decreased fat digestion and absorption due to decreased secretion of digestive juices from the pancreas. Fat can not be absorbed by the small intestine may also have other reasons, it is recommended to consult a doctor in a timely manner, by the doctor to identify the cause of the disease, for targeted treatment.