It is a fact well known to parents that teens, unsurprisingly difficult about a great many things, are also typically surly and uncooperative when it comes to eating well. For their part, adolescents often tell the researchers who study their nutrition habits that they simply aren't set up with the tools for healthy eating: time, access and money.

About 80 percent of teens don't eat a nutritionally sound diet, according to a study released this week in the journal Circulation, using NHANES data from the Centers for Disease Control and Prevention.

"In focus groups we have done with teens, time comes up as their biggest issue in terms of eating better. They say that they know what they should eat (from health classes, etc.) but that their schedules don't allow them to eat that way," says Jamie Stang, Ph.D., MPH, RD, editor of the Guidelines for Adolescent Nutrition Services. "Many of them report participating in school activities after school, plus holding jobs in the evening and on weekends. They then come home and work on homework until early in the morning hours, then get a few hours of sleep and go back to school."

With that kind of tight schedule, vending machines, corner stores and fast food drive-thrus are more accessible and easier on finances made up of allowance money and part-time after-school wages.

Because teens make up a unique population -- one who often fends for itself without necessarily having the resources to do so properly -- it requires a unique set of diet advice. So we asked nutritionists who specialize in adolescent medicine to tell us: How can teens make the changes they need to eat right?

1. Eat Whatever For Breakfast
Just as long as you eat breakfast. Teens are less likely to eat breakfast than adults are, and studies show that doing so can improve the short-term memory and mood of adolescent students.

"Breakfast doesn't have to be cereal or eggs (traditional foods)," says Stang. "Students can eat whatever they have quick access to, such as leftover vegetable pizza, whole grain toast with peanut butter, a sandwich or even a whole grain granola-type bar. If students have this with a glass of milk, they get a pretty good dose of calcium, protein, fiber and other nutrients."

Coffee is okay, says Stang, but coffee drinks -- those sweet confections with whipped cream and syrup on top -- should be consumed in moderation, since they can pack hundreds of empty calories.

2. Keep Snacks In Your Locker

Often, there's not enough time for a healthy lunch during the school day, so teens can keep healthful snacks that don't need to be refrigerated in their lockers as a way to stay full and hold strong against the allure of the vending machine.

"If students don't have time for lunch at school, they can keep items such as low-fat, whole grain granola bars, dried fruit, trail mix, whole grain crackers with peanut butter or cheese, or nuts in their locker to eat between meals," says Stang.

3. Sandwiches For Dinner

Many teens don't have dinner with their families and are left to fend for themselves in the kitchen, meaning they need quick, easy and healthful meals. That's where sandwiches come in. "Sandwiches are usually a good choice if they use whole grain bread and vegetables (easy on the mayo)," explains Stang.

4. Raid The Fridge For Bite Sized Fruits And Veggies (And Parents: Put It There!)

"Parents should keep fruit and cut vegetables or salad mix in an obvious place in the home or refrigerator to encourage teens to use these foods," Stang says.

Heather I. Mangieri, MS, RDN, CSSD, LDN agrees. "When it comes to teens, it is often the parents that I have to talk to as well," she says. "The younger population is less motivated by their health, unfortunately."

In other words, teens will eat the healthy food if it is easily available to them, but might not have the motivation (and time and resources) to put calories there in the first place.

5. Don't Worry About Changes In Appetite

During adolescence, teens' appetites can vary greatly. This depends on growth spurts and hormonal changes, among other reasons (the start of soccer season, for example).

"Physical development doesn’t happen on steady trajectory and their hunger patterns will tend to mirror the uneven growth spurts," according to a curriculum put together by the Center for Adolescent Health at Johns Hopkins Bloomberg School of Public Health.

6. Don't Overdo It

Still, calorie needs for teens are not dramatically different than for children -- regardless of growth spurts. Overeating is still a big concern for teens.

"Logically, caloric needs are higher in adolescents than in children," according to the Johns Hopkins working paper. "However, they may not be as high as you think."

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  • Don't Leave Home Hungry

    "Eat a good meal before you leave," Young says. That'll keep you from grabbing the first thing you find once you get through security. And by eating out of your own kitchen, you'll know exactly what you're putting in your body.

  • Come Prepared

    "If you’re a planner, bring snacks from home," Bauer says. She recommends nuts, seeds or roasted edamame. Or pieces of fruit that won't be messy -- like bananas or clementines.

  • Take A Lap

    "Do not buy the first thing you see," counsels Young. "You can often get healthy stuff if you look for it, so take a lap around before buying."

  • Find The Refrigerated Case

    While shelves are full of chips and candy bars, the refrigerated case is more likely to have hummus, yogurt, low-fat cheese and other healthful picks, according to Bauer.

  • Stay Hydrated

    We often mistake thirst for hunger, so keeping well-stocked in the water department can help stave off hunger pangs. Especially in the drying environment of the airplane, water can do wonders. And, according to Bauer, being hydrated keeps you feeling fresher during your journey.

  • Stick To Individual Portions

    Whether you bring snacks from home or buy them on the road, be sure to choose single portions. "When you’re being held captive on the plane or in the car, it’s easy to overeat and you wind up going through the whole bag … so don’t give yourself the option."

  • Lisa Young's Picks

    Seltzer or water instead of soda Single-serving bag of nuts Whole grain popcorn Mini hummus Baby carrots V8 juice (low sodium if you can find it) Air popped popcorn Noncreamy soup

  • Joy Bauer's Picks

    A bag of nuts or sunflower seeds A piece of fruit Roasted edamame Light popcorn Pistachios Nature Valley or KIND granola bars String cheese Low-fat yogurt Cottage cheese cups Water Sugar-free gum