What does it mean when your stool floats?

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It is a common misconception that floating stool indicates high fat content. Actually, the ability of stool to float depends on the air content: the more air in the stool, the less dense it is and the more likely it is to float.

Floating stool is often seen during episodes of diarrhea caused by an acute gastrointestinal infection. The rapid transit of the food through the digestive tract and bacterial metabolism of certain nutrients lead to a higher concentration of gases in the stool. Once the infection resolves, stool characteristics usually return to normal.

Some patients with chronic diarrhea also have floating stools that are greasy and smell very bad. This type of stool is often seen in people suffering from malabsorption, a dysfunction in the digestive tract that impairs the body's ability to digest and absorb fat and other nutrients. The food that is not absorbed will pass through the digestive tract, producing a watery stool with fat droplets in it. Again, bacteria will metabolize some of the nutrients that end up in the colon and lead to increased gas formation. Thus, floating stools are common in malabsorption.

It is important to discuss a change in the characteristics of your stool with your doctor, especially if these have been present for more than a couple of weeks.