The best way to avoid derailing your diet when you're on the go is to plan ahead. We've tracked down the best portable options, many of which you may already have in your fridge or pantry, so you'll be prepared next time hunger strikes.

If you're going on an airplane…bring nuts

You never know when your next meal will be when you're traveling, so be sure to pack snacks in your carry-on. You want something that will travel well. That means no leaky, smelly or refrigeration-required foods––your seatmate will thank you! Nuts are high in protein, so they'll keep you satisfied longer. Just remember, they're also high in fat––albeit the good kind––so pay attention to portion size or look for single-serving packs.

If you're going on a car trip…bring granola bars

Healthy dining options can be limited when you're on the road. To avoid pulling over at a fast-food restaurant, pack granola bars. This fiber-rich treat will keep you satisfied for the long haul. Even if you're not going on a road trip, keep a supply in your glove box in case you get stuck in traffic and need a pick-me-up.

If you're going to work…bring vegetables and fruits

It's easier to resist the morning-meeting muffin basket or the afternoon trip to the vending machine if you come to the office prepared. Fruits and veggies make for healthy, low-calorie snacks that are perfect between meals. If you're craving crunch, reach for carrot sticks or sliced cucumber. Satisfy a sweet tooth with your favorite in-season fruit. If you need an extra afternoon pick-me-up, dip your veggies in hummus or spread peanut butter on an apple or banana.

If you're going to the gym…bring an energy bar

Heading to the gym famished will cause your workout to suffer. An energy bar provides the fuel you need to power through a sweat session. Just be sure to look for one that's low in fat and calories, but high in fiber. Stash these in your gym bag to prevent arriving at the health club hungry.

If you're going shopping…bring a low-fat cheese stick

When you're at the mall and hunger strikes, don't fall prey to the food court. Throw a light cheese stick in your purse and you'll have a protein-rich snack that will tide you over until your next meal. Plus, you'll feel more confident trying on clothes after making a healthy choice.

If you're going to the movies…bring light microwave popcorn

You can reach your daily calorie quota with a large, no-butter added, movie theater popcorn. Resist the temptation of super-sized popcorn from the concession stand by bringing your own bag from home. You'll get the same satisfaction from light microwave popcorn and besides cutting calories, you'll also be saving money.