Stools that float are usually due to poor absorption (
Floating stools are seen in a variety of different situations. Most are diet-related, or occur during 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.
Acute gastrointestinal (GI) infections also 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 makes it less dense and allows it to float.
Increased levels of nutrients in the stool that have not been absorbed by the GI tract supply 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.