Stools that float are generally associated with some degree of malabsorption of nutrients or excessive flatus (gas).

Floating stools are seen in a variety of different situations. Most are diet-related, or caused by episodes of diarrhea that accompany a gastrointestinal infection. A change in diet can lead to an increase in the amount of gas produced by the bacteria found in the (healthy) gastrointestinal tract.

Similarly, acute gastrointestinal (GI) infections can result in increased gas in the intestines, due to rapid movement of food through the GI tract. One wrong idea is that floating stools are caused by an increase in the fat content of the stool. In fact, it is increased gas in the stool that make it less dense and allow it to float.

Another cause of floating stools is malabsorption, in which the body can't properly digest and absorb fat and other nutrients from the GI tract. More than 2 weeks of diarrhea with floating stools is often seen in people suffering from malabsorption.

Increased levels of nutrients in the stool (which have not been absorbed by the GI tract) are supplied to the normal bacteria that live in the gut. These bacteria in turn produce more gas. This results in more gas-rich stools that float.

Dietary changes, diarrhea, and malabsorption can cause floating stools. Most causes are harmless and the floating stools will go away by themselves when the infection ends or the normal bacteria in the GI tract adjust to the changes in the diet.

The following diseases may also cause floating stools:

• Abetalipoproteinemia
• Biliary atresia
• Cystic fibrosis
• Disaccharides deficiency (insufficient amounts of the sugar-digesting enzymes lactase, sucrase, or isomaltase)
• Gluten-induced enteropathy (sprue or celiac disease)
• Idiopathic steatorrhea (fatty stools with no known cause)
• Short bowel syndrome