Fatty Stool – Causes of Steatorrhea, Greasy, Oily Bowel Movements

The term ‘fatty stool’ is used to describe stool that is greasy or oily, often floats and is bulky. The medical term for this type of fatty stool is steatorrhea. It may also appear frothy, gray to pale yellow. The presence of mucus in the bowel movement is often mistaken for fatty stools and therefore a stool test is essential to conclusively identify steatorrhea.

In mild cases, steatorrhea may remain unnoticed for long periods of time. Patients may only report noticing some greasiness upon wiping and that some bowel movements may result in floating stool, often only after eating fatty meals. In severe cases, the appearance of the stool is clearly abnormal.

Causes of Fatty Stool

As discussed under What is Steatorrhea, fats in the stool may be a result of impaired digestion of fats, decreased absorption or both as is seen in rapid transit time.

Digestion Problems

Fat digestion primarily depends on the action of pancreatic lipase although other fat-hydrolyzing digestive enzymes are also responsible to a lesser extent for fat digestion. Some of the conditions that may result in a disruption in the digestion of fats includes :

Absorption Problems

Malabsorption syndromes are often characterized by steatorrhea. The causative conditions affect the absorption of fats through the intestinal lining and transport of fats through the lacteals. The formation of micelles is impaired with small bowel bacterial overgrowth, which is necessary for the absorption of fats into the epithelial cells lining the small intestine.

  • Celiac disease
  • Inflammatory bowel disease, particularly Crohn’s disease
  • Small bowel bacterial overgrowth
  • Abetalipoproteinemia
  • Whipple’s disease
  • Excessive use of slimming tablets containing orlistat

Rapid Gut Transit Time

The transit of chyme through the gut is carefully regulated in order to ensure there is sufficient time for the digestive enzymes to act on food and absorb through the intestinal lining. Any increase in the transit time may affect the digestion and absorption of nutrients, including fats.

  • Diarrhea
  • Possibly irritable bowel syndrome (diarrhea-predominant IBS)
  • Short bowel syndrome
  • Excessive use of laxatives