Here at HiLine, we try to address all of your burning coffee questions (and please, stop burning your coffee). In that spirit, we're passing along this nugget from the Huffington Post, which recently asked, Why Does Coffee Make You Poop?
Let's, um, get to the bottom of this, shall we?
In this instance, we'll skip the anecdotal evidence (you're welcome) and let science do the talking. Caffeine is a known diuretic. That means that in addition to increasing the frequency of urination, the stimulants in caffeine also act on the muscle tissue in the digestive tract, moving your last meal along with a bit more dispatch than you might've anticipated. The reason that a can of Coke doesn't typically have the same effect comes down to the concentration of caffeine (~34 milligrams per serving of soda, versus anywhere from 80 to 175 milligrams for coffee, depending on the brew method).
Other factors also have a bearing in caffeine sensitivity. Sex plays a role, as do an individual's activity levels and tolerance for caffeine. Diet plays its part, too, as acidic foods, fatty foods, dairy and non-dairy creamers can all increase bile production. Many artificial sweeteners can cause gas and bloating by interfering with users' gut bacteria. And that's before we take into account lactose intolerance, which complicates matters still farther.
Need a little get-up-and-go? We've got just the thing!
So where does that leave us?
The takeaway, besides not having an artificially-sweetened yogurt with your morning coffee: different people have differing reactions, and sensitivity, to caffeine. While the average person ingests about 200 mg of caffeine per day (the equivalent of two cups of coffee), the effects felt can vary depending on how much is ingested at once, and when it's ingested. If you have a higher sensitivity to caffeine, or if you have a sensitive stomach, you'd do well not to have that 200 mg in one sitting. Pace yourself, or change one of your coffees to decaf, if you notice a problem. Your digestive system, your significant other, and your co-workers will thank you for it.