A GI doctor explains why so many people get so backed up away from home.

You blocked off a week, enabled your out-of-office email reply, and mentally high-fived yourself for taking a much-deserved break. Now that you're actually on your trip, you should be feeling great—yet something is just a little off.

Maybe you feel bloated, gassy, or even have some stomach pain. And now that you think about it, it has been a few days since you've gone number two.

What's going on? It's called vacation constipation (aka travel constipation), and experts say it's super common, even if you're the type who never has trouble pooping. So why does it strike when you travel? "A lot of times it's just the change in routine, coupled with the extra stress of traveling," says gastroenterologist Vijaya Rao, MD, assistant professor of medicine at The University of Chicago School of Medicine.

Vacation constipation can start while you're in transit; taking a long road trip or plane ride often means limited access to bathrooms (especially the clean and comfortable variety). Once you're settled into your hotel, it's still not quite home, so your bowels might be feeling shy. Dietary changes are also a major factor, since you're probably eating different foods than you do at home.

Sleep disruptions—especially if you've changed time zones or ended up on a lumpy pull-out sofa—can also impact your ability to poop regularly, as research has found an association between sleep disturbances and bowel symptoms.

While vacation constipation isn't the worst thing that can happen when you're away from home, it's not exactly fun. Luckily there are ways to prevent it or get your bowels moving again if it does strike. Here's your 3-part plan.

Before your trip: consider probiotics

Dr. Rao says more research is needed, but it can't hurt to take a probiotic supplement or eat yogurt with live cultures before you hit the road. For best results, get into the habit of consuming probiotics (kimchi, sauerkraut, tempeh, and yogurt are good options) at least a few days before you leave home and continue throughout your time away. Some research suggests that the good bacteria in probiotics might soften stools and ease constipation.

In transit: Get out of your seat often

If you're flying, don't just sit there: Get up and walk the aisles to keep the blood flowing in your legs and well as in your gut. If you're traveling by car, take frequent breaks to stretch your legs for a few minutes. "Regular exercise promotes daily bowel movements," says Dr. Rao.

Meanwhile, avoid the urge to nibble on junky airport snacks like potato chips and chocolate bars; your colon will be happier if you munch on high-fiber fare like dried fruit and nuts. And don't forget to drink lots of water. Staying hydrated is crucial for good gut motility.

At your destination: Move, eat, and drink lots of water

"Try to preserve as much of your regular routine as possible," says Dr. Rao. She also advises paying close attention to your food choices throughout your trip. Of course you'll want to indulge and sample local delicacies, but try to incorporate fiber-rich foods like fruit, vegetables, oatmeal, and lentils into each day. Walking around as much as possible is also helpful, as is continuing to sip water. Get a good night's rest at the end of each day too.

If all else fails and you feel uncomfortably plugged up, Dr. Rao's laxative of choice is Miralax, which she says is much safer and gentler than stimulant laxatives. Just mix the powder into at least eight ounces of fluid. This will help draw water into your colon . . . and encourage the pooping process.