Floating poop: what does it mean?

Why does poop float?

MedlinePlus, the US National Library of Medicine’s health site, keeps it simple: most of the time, floating stools are due to what you eat. A change in diet can increase gas, and more gas in the stool lets it float.

It also says:

• most causes of floating stools are harmless
• floating stools usually go away without treatment
• floating stools alone are not a sign of illness

A gastrointestinal infection can also cause floating stools for a while.

Which foods might do it?

MedlinePlus doesn’t list specific foods for floating poop, so we won’t make up a list. But the NIDDK explains that gas forms when bacteria in your large intestine break down carbohydrates you didn’t fully digest. Foods that give you more gas are a sensible place to look. If you’ve recently added a lot of beans, lentils, certain vegetables or fiber, that’s a likely suspect. Our foods that cause bloating page covers the usual ones.

When is floating poop worth checking?

MedlinePlus singles out one combination: floating, greasy stools that are foul smelling may be due to severe fat malabsorption, particularly if you’re losing weight. Malabsorption means your body isn’t properly absorbing fats or other nutrients. (Our glossary has a plain-English entry on malabsorption.)

Talk to a doctor if floating poop comes with:

• a greasy or oily look, or it’s very hard to flush
• an unusually bad smell that sticks around
• weight loss you can’t explain
• pale or clay-colored poop (see pale poop)
• ongoing diarrhea

Contact a provider right away if you have bloody stools with weight loss, dizziness and fever.

Conditions that can affect how you absorb food, like coeliac disease, can cause diarrhea that the NHS describes as smelling particularly unpleasant. Only a doctor can test for these, so it’s better to ask than to guess.

What should I write down?

If you’ve noticed floating poop more than once, a few notes go a long way:

Mon 12:30  Lunch (photo): lentil soup, rye bread  tags: FODMAPs, gluten
Tue 08:10  Poop: type 5
Tue 08:10  Paper note: floated, normal smell
Wed 08:00  Poop: type 4
Wed 08:00  Paper note: sank

If your notes look like this, with floaters after gassy meals and nothing else going on, that’s the harmless pattern MedlinePlus describes. If they say “floated, greasy, hard to flush” most days, and you’re losing weight, bring them to your GP.

PoopAI logs the meal and the Bristol type, with an optional photo. “Floated” or “greasy” are notes you’d add yourself, on paper or in a notes app.

What will a doctor ask?

MedlinePlus lists the kinds of questions you might get:

• When did you first notice it?
• Does it happen all the time or from time to time?
• What’s your usual diet, and does changing it make a difference?
• Are the stools foul-smelling, or an unusual color like pale or clay?

A short log answers most of those in one glance.

Questions to ask yourself

One floating poop tells you very little. A pattern tells you more. Ask: did I eat something gassy or unusually high in fiber yesterday? Is it every day, or once in a while? Does it also look greasy, leave oily marks or smell much worse than usual? Have I lost weight without trying? Log each poop’s Bristol type for two weeks and add a quick paper note when one floats. If floaters come and go with certain meals, that’s reassuring. If they’re constant, greasy or come with weight loss, that’s the moment to book a GP appointment and bring your notes.

Wrap-up

Floating poop is usually just gas and diet. Watch for the greasy, smelly, weight-loss combination, and don’t sit on it if you see blood. Otherwise, it’s one of those things your body does that sounds stranger than it is.