A deep dish pizza in Chicago, Tex-Mex in Dallas, an eponymous cheese steak sandwich in Philadelphia, and another slice of pizza in New York City ... Many of the most often-visited cities in the U.S. are synonymous with their native food--and let's not even start with German beer or French cheese. While it would be a shame to miss out on experiencing authentic local fare, it might not be worth coming home with a few extra pounds as a souvenir.

"When you're on vacation, it just feels natural to let down your healthy eating guard," says Shereen Jegtvig, a nutritionist of 16 years and current nutrition guide on About.com. "Maybe you can do that for a meal or two, but if you pig out every time you eat, you're going to feel tired, unhealthy and just plain yucky long before your vacation is through. Then you're going to have extra pounds to lose when you get home."

Plan Ahead for Healthy Eating

Whether you're traveling for business or pleasure, it's always a challenge to maintain a healthy diet on the road, but certain "trouble times" are worse than others. Jegtvig says women are more susceptible to eating unhealthy food when stopping at junk-food-filled gas stations when you're hungry, being rushed at the airport, or loitering in the concourse when a flight is delayed and you're tempted by the food court.

"The best way to combat the trouble times is to be prepared," she says.

Take it from an itinerant traveler; Shelley Fasulko is a project director at IEG and spends about a third of the year on the road meeting with clients. After room service and expense-account dinners started affecting her waistline, she adjusted her diet and has even been able to lose weight while traveling.

"If I'm really prepared with all my snacks and quick meals, I actually feel that I eat a bit more healthfully because there's no impulse factor," says Fasulko. "However, if I'm unprepared I tend to eat much worse."

What to Eat While Traveling

One of Fasulko's favorite moves is measuring cereal into individual baggies and bringing along disposable silverware so she can just add milk and eat on the run. She also seeks out portable snacks at the grocery store - such as individual peanut butter packets and granola bars - that travel well without refrigeration.

If you have access to a cooler, Jegtvig recommends loading up on fresh-cut fruits and vegetables or individually wrapped servings of cheese and crackers.

When you are caught unprepared, don't get lazy; most airports have a convenience store with dried fruit, mixed nuts and/or granola bars that are much healthier than fast food options.

Tips and Tricks from the Road

"One tip - which is sort of cheesy - is that I'll bring one of my books that is all about healthy eating. If that's my reading material while I'm traveling it's pretty tough to justify a cheeseburger and fries for dinner," says Fasulko. "It doesn't always work, but sometimes it does the trick."

If you're still having trouble fighting off your urges to eat unhealthy food, try something else psychosomatic (like Fasulko’s book trick), as chances are good you’re only eating to comfort yourself and a quick assessment of your mental state could save you some calories.

"Try to keep your attitude in check; remind yourself that you're not traveling just to eat, you're there to visit friends and family, see the sights, and enjoy non-food related things," says Jegtvig.

"And, I have to admit, if I'm going somewhere warm and I'll be wearing short shorts or a bikini, the mirror is pretty motivating too."

Mark Collins is a freelance writer in Austin, Texas.