(CNN) — The alarm goes off at 4 a.m. and you drag yourself out of bed. You eat nothing -- it's too early to stomach food.

It's a two-hour commute to the nearest airport. At Departures, growing hunger pangs are curbed with a pre-prepared sandwich from the nearest food outlet followed by snacks in the business class lounge.

Over a six-hour plane journey, you alternate between struggling to sleep, working on upcoming presentations and feasting on the food and alcohol you're being offered. You might not really be that hungry -- but it's there and it's free -- so you're going to eat it.

During your five-day work trip, the combination of sleep deprivation, jet lag, business dinners and hotel buffets wreaks havoc on any plans to try to retain "at-home" meal routines.

You return home feeling bloated and unhealthy -- on top of your unavoidable tiredness.

Welcome to the world of the traveling executive. Behind the glamor of free business class travel lies the truth -- a mess of unpredictable nutritional schedules and dietary temptations.

"Research shows that those who travel for business for two weeks or more per month have higher rates of obesity compared to those who travel less often," dietician and author Lisa Drayer tells CNN.

Even the most health-conscious business travelers struggle to maintain a healthy lifestyle while traveling.

Be prepared

l e v a r t

But does it have to be this way?

Porter is an expert on helping frequent travelers manage their diets.

"I'm also married to a traveling sales director," Porter laughs, "So I talk the talk and walk the walk."

Porter advises that preparation is key. Travelers should bring their own snacks to avoid being tempted by unhealthy options along the way:

"In your travel bag or car, you should pack things like almonds," suggests Porter. "Have some fruit -- citrus fruits travel well. Get to know what you can buy on the go."

Drayer consolidates Porter's advice: "I always say: if you fail to plan, you plan to fail [...] One of the most important things that you can do is pack snacks with you."

"Try to do vegetables as well as fruit," advises Porter. "Get to know what you can buy as a healthy snack on the go -- and what you can carry on the plane with you."

In transit

Go easy on the complimentary Champagne. Courtesy Emirates

Airplane food has a bad rep even in business class, and a 2015 survey found that many US airlines are failing to offer nutritious, low-calorie options

Porter does not caution against airplane food completely -- rather, she suggests sticking to a normal meal schedule as much as possible.

"It's very tempting if people put food in front of you to eat it," she says. "If that meal coincides with when you have a meal that's fine, but the problem is that people might have lunch and then eat on the plane and then have dinner as well.

"Also make sure you stay hydrated, it's fine to drink -- but people should remember alcohol has calories and alcohol dehydrates you -- stay within your limits."

For some, the stress of traveling makes them lose their appetite, but Porter cautions against going for long periods of time without food -- "because then when you get food you might overeat."

Eating out

In everyday life, most people probably don't eat out regularly. But on a business trip, they might dine out daily.

The temptation is to treat yourself, as you might at a restaurant at home -- but Porter cautions against this mindset.

"If you know you're going out for a big business meal, eat light in the daytime," advises Porter. "Try and stick with one course and order extra veg or a green salad. If you have a dessert -- have a non-creamy one or fruit.

"Watch portion sizes in places like America. The maximum red meat you should consume is 500 grams a week -- and if you get an eight-ounce steak for dinner that's about 250 grams. A couple of those in a week and you've had all your red meat."

Sian explains that travelers should not be afraid to be assertive in restaurants -- "you're the customer!" she stresses.

Want your food cooked a certain way, or to substitute extra vegetables for fries, don't be afraid to say so?

The temptation to feast on bread should be avoided too.

"Avoid bread and butter and extras like garlic bread, ask for sauces to be served separately," says Porter.

Meanwhile Drayer cautions against salads, which can be "all over the map in terms of calories [...] You want to choose a low-calorie salad [...] You know, lettuce, a lot of vegetables, and a low-fat dressing like a vinaigrette."

Breakfast time

The call of the buffet is strong -- go easy on the bread. Ralph Orlowski/Bongarts/Getty Images

They say breakfast is the most important meal of the day -- so travelers should avoid skipping it, even if their internal clock is out of balance.

Hotel buffets should be resisted too.

"Step away from the buffet!" cautions Porter.

"It's important to have protein, to choose things like eggs and mushrooms. Try to include some fruit and try to avoid sugary cereals. When you're choosing toast go for wholegrain."

Drayer agrees that proteins is best for keeping hunger at bay.

"You're less likely to snack frequently if you've had protein as a big part of your meal," she says.

There are also warnings about going overboard on the espresso machine.

"Caffeine can help with jet lag," Porter concedes, "But you don't want to have more than 3-5 cups of tea of coffee a day. Don't rely on caffeine."

If you're wilting, Sian advises eating carbs over confectionery:

"It's much better to have a wholegrain sandwich than grab a Mars bar, say -- otherwise it'll just be a sugar hit..

The psychology of eating

For anyone used to dinner being catch-up time with family or partner, eating alone in a hotel bar might be hard to stomach.

Loved ones are missed and loneliness sets in.

But Porter cautions against using food as a reward:

After the "fasten seat belt" light goes off, get movin'. CNN's Rachel Crane learns a few yoga moves to avoid stiffness and blood clots during a long flight.

"Because you're essentially spending your evenings still at work, many people use food as a reward. They think 'I'm eating on expenses, I've got to be here so I will reward myself by eating a pudding or chips.'

"The trick is to try and think of something else that isn't food-related that's a reward. Why not book a hotel with a spa so you can have a treatment -- find something that you can do that isn't eating.

"Be mindful that there's a psychology of eating, that's a well-worn path that a lot of executives go down: 'I'm miserable but at least I can put the alcohol and food on expenses.'

"Imagine what your partner would say!"

Realistic?

So is a normal diet ever possible for a frequent traveler?

"The ideas and advice from the dieticians is thought-provoking," says one executive frequent flier. "But implementing those strategies every day -- and trying to get a routine whilst on a work trip -- is not easy.

"The defining feature of business travel is it is not routine. That said, it's definitely given me some ideas for next time."