Hello, I understand your concern. Fat in the stool is also called steatorrhea, and presents as bulky stools of a pale and oily appearance that can be particularly foul-smelling. The fats and lipids are usually completely digested and absorbed in our body, and in case this digestion and/or absorption mechanism is impaired it results in fatty stools. There are several reasons that the fat digestion or absorption may not function properly. One of them is related to the pancreas. Insufficiency of the enzyme lipase (responsible for fat digestion) produced in the pancreas can be a main reason. A test that measures pancreatic enzymes would be the sensible thing to do. Another reason can be related to the gallbladder or the liver. Bile salts are essential in fat processing. A third reason can be certain conditions that affect fat absorption in the intestines, such as celiac disease, inflammatory bowel disease, abetalipoproteinemia and bacterial overgrowth. Certain drugs can also be responsible for steatorrhea, such as weight loss pills or orlistat. Finding out the cause for this condition requires a visit to the doctor who will take a more complete medical history and order the appropriate tests. Wishing you good health and all the best.