Bowel movements can float for a number of reasons: The two most common reasons for floating stools are excess gas and poor absorption of nutrients, reports Healthline. Other, less common reasons include celiac disease, short bowel syndrome and several extremely rare genetic diseases.
Diet is the top reason that feces float rather than sink as normal, since consuming foods high in lactose, sugars, starch or fiber can produce excess gas, which is passed in the stool, explains MedlinePlus. Those who suffer with lactose intolerance may also have frequent floating stools as the intolerance can cause diarrhea and malabsorption. A doctor should be contacted if floating stools are accompanied by other symptoms, such as blood in the stool, dizziness and weight loss.