One of the more enduring selling points of travel is the promise of leaving much of our day-to-day routine at home. The part of it we too often leave behind, however, is our healthy diet.

Did I lose you at “healthy” or “diet”?

For the sake of argument, let’s say that against the backdrop of a stressful economy, family, or relationship, you don’t maintain the healthiest of eating habits. If that’s the case, your next trip, beginning with the plane ride, might be a good time to start.

Have a scotch and water, hold the scotch.

Headaches, indigestion, constipation, fatigue, hunger. If you experience any or all of these when you travel — or anytime — it could be for any number of reasons, but often all of these conditions can be linked to varying degrees of dehydration. Drinking more water overall, but particularly in flight — about 8-12 oz. per hour — will help keep your body in balance. You’ll keep your budget in balance, too, if in lieu of buying that overpriced bottle of water that’ll be confiscated at the security checkpoint, you bring along an empty plastic or BPA-free stainless steel bottle to refill later at a water fountain, suggests Ivonne Berkowitz, a health coach at Take Care Health Systems. While you’re at it, curb your caffeinated and energy drinks, whose sugars and stimulants can wreak havoc on your energy levels, she says, especially if you’re trying to adjust to a new time zone.

Likewise, avoid most of what’s on the in-flight beverage cart, beginning with regular soda. “It's nothing but sugar,” Berkowitz says. “Fruit juice is not all that much better, usually, especially the liquid they pass as ‘juice’ on board, often giving you as many grams of sugar as the regular soda would.”

And while some in the medical and scientific communities argue that caffeine’s ability to dehydrate is exaggerated, there’s little debate that alcohol dehydrates us and ranks very low on the list of ideal passenger in-flight beverages. According to nutritionist Monika Woolsey of Air Vitals, which provides health coaching to flight crews, “We have this delusion that alcohol helps us to fall asleep. That may be the case initially, but it then disrupts the quality of sleep. We can feel groggy the next day, which is when we over-consume caffeine and sugar for energy.”

If this vicious cycle doesn’t faze you and you were hoping even to save a few bucks by carrying on some liquor minis, keep in mind that it’s against federal law to serve yourself alcohol on board.

Think fiber and protein.

“One of my favorite low-fat travel foods is oatmeal packets. I just stop by the coffee shops in the airport and ask for an inch or two of hot water. Soup cups work well, too,” says former flight attendant Beth Blair, a contributor to the blog Traveling Mamas. “Liquid foods” like these, as well as high-in-water fruits and vegetables like apples and celery not only help hydration, but are also often high in fiber, which can be particularly beneficial, Woolsey notes, since inactivity and insufficient hydration in flight can promote constipation. Conversely, she notes that diarrhea is often about stress, and if aspects of travel make you anxious, you should eat some "low residue" or low-fiber foods a day before your trip.

Our bodies tend to need a lot of protein to work properly, and that’s especially true when we travel. “Protein, as opposed to carbohydrates, may help you to feel more alert,” Woolsey says. “That may come in handy if you have a tough travel schedule and your sleep patterns are therefore being disrupted.”

She adds that a high protein diet helps keep our blood sugar more stable, which in turn helps reduce our appetite for sweets. Among Berkowitz’s favorite easy-to-pack high-protein snacks are low-fat cheese, beef and turkey jerky, hard-boiled eggs, and natural peanut butter on whole-grain bread.

Be wary of many of the protein bars out there, especially if you’re watching your waistline. “Look at sugar content — many of them are just fancy candy bars,” Woolsey says. “And look for types of fat. If the label says ‘hydrogenated’ or ‘partially hydrogenated’ it's a trans fat. I also advise clients to stay away from ‘S’ and ‘C’ oils—any oil beginning with those letters, except for canola, is more pro-inflammatory and likely to aggravate everything from cholesterol levels to weight to fertility.”

Try the 80/20 rule.

If maintaining a healthy road diet isn’t enough of a challenge, add a child or two to the mix.

Suzanne Rowan Kelleher, mother of three and co-founder and editor-in-chief of family travel site WeJustGotBack.com, advocates the 80/20 rule, trying to make “healthy foods account for at least 80 percent of what your family eats. When you pack your own healthy snacks, you're less likely to reach the starving point and head for a fast-food outlet or candy rack in the airport. I like to bring portion-controlled snacks, such as PB&J sandwiches, granola bars, single-serving bags of Goldfish crackers, popcorn, or pretzels, or pieces of fresh fruit.”

Set boundaries on the ground.

Sandwiched between your flying days, of course, is the trip, and if you stick to some simple rules, you can eat right and still take advantage of your destination’s culinary bounty.

Woolsey cautions against “stress eating” on trips when our schedules and normal environments are disrupted. Further, she says frequent travelers are prone to overeating out of habit when they “begin to associate certain cities with certain foods, and they go to the same places because the routine is a sort of comfort.”

Overeating is also easy to do when we don’t control our portions. Susan Black, a travel industry consultant who’s on the road 30% of the time, says when she dines out, size matters.

“I make a fist, and eat only the size of my fist. Overindulging is usually the quantities one eats....so I leave over more than I eat," said Berkowitz. “If you're going to go all-out at a breakfast place, you might get back to your healthier every-day options the rest of that day. If you're planning a nice dinner at a one-of-a-kind local restaurant that night, then expect to have a low-key breakfast and lunch. “

Ann Lombardi, tour leader and co-owner of The Trip Chicks, has seen a lot of questionable eating habits among vacationers in the 67-plus countries she’s visited, and among the basic habits she encourages on her tours is de-emphasizing late or hefty dinners. “The closer you eat to bedtime, the more tempted you are to gorge,” she says, adding that a light dinner could even be a relatively inexpensive picnic incorporating low-salt, low-sugar basics you buy yourself.

Keep it up at home.

Whether we’ve gone all out, tried the 80/20 rule, or some regimen in between, there’s often a temptation to stay on a less-than-healthy “vacation diet” for a couple days after getting home. At least that’s my strategy.

Woolsey suggests that’s the wrong way to look at it.

“One thing we could all be better at is not compartmentalizing ‘at home’ and ‘travel,’" she says. “When we do that, ‘travel’ denotes ‘no rules.’ If your mindset is that you have certain guidelines you wish to follow over the long term, ‘travel’ should really mean ‘circumstance 2’ for following those guidelines...not ‘permission to ignore the guidelines.’"

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