How what goes in comes out

Warning: If you have an aversion to your body's waste, don't read any further.

However, your stool can tell you a lot about your diet and health. And who better to tell us a bit about our poo than Dr. Anish Sheth, a gastro­enterology fellow at the Yale School of Medicine and co-author of What's Your Poo Telling You? (Chronicle Books, $9.95). Here are a few diet scenarios and how they affect your poo:

Anti-diet: white toast, no fruits or veggies (no fiber)

A lack of fiber causes infrequent, hard stools that require straining during defecation. Fiber, in ­insoluble and soluble forms, is vital to soften the stool and aid in its effortless passage through the GI tract. Low-fiber diets produce dry, pebbly stools and, in severe cases, can result in fecal impaction — in which stool forms a rock-hard plug that prohibits passage of any stool at all.

Plant eater: steamed broccoli, tofu burger, apple and asparagus

Vegetarians tend to eat balanced diets high in fiber. The good news is that their stools are frequent and soft in consistency, making trips to the loo satisfying and enjoyable. The downside can be gas. Because our bodies are unable to digest many of the plant products we consume, these substances undergo fermentation by the bacteria in our colons. The formation of carbon dioxide causes bloating and excessive flatus production but is otherwise harmless.

Carnivore's delight: big order of prime rib

When red meat gets digested, it produces compounds called mercaptans. These are sulfur-containing molecules that lend feces and flatus their rancid odor and account for the general notion that red-meat consumption produces a particularly rancid-smelling poo. Incidentally, population studies have linked diets high in red meat with higher rates of colon cancer.

Plop plop/fizz fizz: spicy gumbo and jambalaya shrimp, hot chicken wings

Spicy food might taste good going in, but its exit is not always as pleasant. The very last portion of the anal region is lined by the same type of cells that line the mouth. This means that buffalo wings can sometimes burn just as much on the way out as on the way in. Spicy foods, in general, are irritants to the GI tract (stomach, small intestine, large intestine) and can speed up the passage of material through the digestive system. The result can be watery stool, occasionally red in color (depending on the ingredients added to the sauce), that exits with a burn.

Fiber everything: bran cereal, whole-grain bread, black beans, brown rice

Pure bliss. This diet maximizes your chances of achieving ”poo-phoria.“ There is no such thing as eating too much fiber (although you might feel bloated and pass flatus more than the average person). Fiber has the ability to retain water and lends stool its cohesiveness and pillowy softness. It also lubricates the inside of the colon, nourishing colonic cells and creating a friction-free environment for contents traveling down the GI tract. The main caveat here is to drink a lot of water. Consuming fiber without water can cause your stools to become harder by adding bulk but not moisture.

Celebration night: Mojitos and cosmopolitans galore (alcohol)

With DADS (day-after-drinking stool), it's liquid in, liquid out. Alcohol is a gastro­intestinal stimulant, a direct irritant to the lining of the intestine that speeds up passage and causes diarrhea. Some drinks are worse than others (malt liquor being particularly potent). Stool comes out in liquid form, usually normal in color and smell and occasionally with excess mucus. There is no antidote for the GI tract — although drinking clear liquor (such as gin or vodka) might be less problematic and causes fewer hangover symptoms.

Grease ball: Fries, pizza, bacon, fried eggs and fried chicken (fried foods)

As long as your pancreas, liver, bile ducts and intestines are working properly, fatty foods should be tolerated just fine. Visibly fatty/oily stools that smell horrendous, are yellow, float and require multiple flushes usually indicate a problem with fat digestion. Other than that, fatty foods tend to give us a sensation of satiety, or ”feeling full.“ This might be due to the release of certain hormones that affect the brain and also due to the longer time that fatty food remains in the stomach (fats take longer than proteins or carbs to empty from the stomach).

Gulp and rush: 60-second meals on the run

Eating quickly (depending on what you eat) and/or not chewing completely has very little effect on the stool but presumably can worsen symptoms of acid reflux and indigestion by causing rapid distention of the stomach and refluxing of contents into the esophagus.

Charles Platkin is a nutrition and public health advocate, founder and editor of, and author.