Help! What causes the presence of fat in a stool?

Small amt normal. Small amount of fat in stool is normal ; fatty stooltends to be foul smelling, pale/yellowish, bulky, sticky, greasy, sometimes with oil droplets in toilet. Can be with intestinal problems, e.g. Celiac sprue, crohn's disease, tropical sprue, parasites, pancreatic insufficiency. Can be from olestra, (wow potato chips-poorly digestible fat), or Alli (causes malabsorption of fat), gastro bypass surg.