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Does Coffee Actually Make You Poop? We Squeezed Out An Answer

Coffee hits everyone differently.

Contributing Writer
​A cup of coffee with poop emoji foam art surrounded by beans.

A cup of coffee with poop emoji foam art surrounded by beans.

You probably think that coffee makes you poop. But does it? The answer is a solid maybe.

Popular culture holds that coffee makes us poop, but the science is a bit more equivocal. Some studies suggest a firm yes, others a looser no. As little as a third of us may actually be ‘Coffee Poopers.’ What seems to be coming out, overall, is that either you are a coffee-driven pooper, or you aren’t. There are no occasional Coffee Poopers.

Interestingly, at least one study also showed a substantial difference in results between women and men. Ladies are, apparently, much more likely to be induced to squat than their male counterparts. These kinds of biological differences are strikingly common but largely ignored when it comes to sex differences, which is one reason that there are substantially more medical complications in women than men.

On a lighter note, another Coffee Pooper study measured rectal tone, with or without a cup of coffee, while post-enema volunteers blew up a “party balloon”. It isn’t entirely clear to me that the researchers didn’t do this study just to see if anyone would volunteer. Tone was measured with a balloon inserted into the rectum. The authors were clear that separate balloons were used.

But why does coffee make us, or at least some of us, poop? We used to think the magic was in the caffeine. The magical molecule that lifts the morning fog and lightens our afternoon mood could also be kick-starting our morning trip to the porcelain throne. A study of rats called that conclusion into question. Coffee wakes up our little rodent friends, just like it does us. It also makes them poop more. But so does decaf. The poop propensity pattern seems to be the same in people. Some studies in people show that decaf has almost as much an effect on priming pooping as typical black coffee. Brewed coffee contains thousands of compounds, any one of which could play a role in hustling along our morning ablutions.

Maybe not surprisingly, head games play a big role. Whether or not you think coffee makes you poop seems to affect whether or not it does (although not in rats; they are coffee pooper agnostics). If you think coffee will make you poop, it more likely will. This kind of placebo effect is common in the world of coffee biology. Coffee is a complicated beverage. Apparently, its ties to pooping are, too. All of these complications and caveats are par for the course when we look at the larger-scale effects of coffee on our bodies and biology.

This is the second piece in a series exploring the science of coffee and coffee drinking. I have some ideas I’d like to explore; cancer, climate change, and decaf come to mind. I would also like your ideas. What topics would you like to know more about? Drop me some suggestions in the comments section below.

    Thomas Merritt
    Contributing Writer
    Thomas Merritt is a contributing writer for MTL Blog.
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