Usually, diarrhea after eating lard may be related to physiological factors such as excessive fat in lard which is not fully absorbed or pathological factors such as pancreatic diseases, hepatobiliary diseases and enteritis. 1. Physiological factors: lard contains a lot of fat, and fat is not easy to be absorbed, when eating too much lard may lead to lard fat can not be fully absorbed by the intestinal tract, diarrhea may occur. 2. Pancreatic diseases: If you suffer from pancreatic diseases such as pancreatitis, it may lead to the body can not be good secretion of pancreatic lipase, then there will be a decrease in the ability to absorb fats and oils, which may lead to diarrhea after eating lard. 3. Liver and gallbladder diseases: If the patient has liver and gallbladder diseases, the function of bile secretion of liver cells may be reduced, which may affect the decomposition and absorption of fat, thus causing the patient to have diarrhea after eating lard. Eating lard diarrhea may also have other reasons, it is recommended to go to the hospital in a timely manner, clear the cause of the disease, under the guidance of the doctor for formal treatment.