There are things in life you never want to put in your mouth: your foot, dirt, electrical cords, and airline food. The latter, airline food, is something some people don't have to worry about anymore. Many flights no longer serve full meals and instead hand out a bag of crackers and a soda the size of a shot glass. This lack of food might be better than handing out an entire airline meal. Unless you're sitting in first class, an airline meal is sure to sit in your stomach like a rock.
With the lack of food, or at least the lack of edible food, airplanes are often things that allow hunger to take flight. This leaves people helpless. Getting up and going to a diner or a cafeteria isn't exactly feasible. For this reason, it's important to take snacks on your flight that will leave you satisfied without contributing to jet lag or airsickness.
Candy: Yes, candy may go against everything you've ever read in the brochures at your doctor and dentist office, but candy is a great airline food. Not only is it easy to transport, but it also helps to hold you over as you go from point A to point B. The chewing motion most candy requires can also help to keep your ears from becoming uncomfortably clogged as altitude increases.
Trail Mix or Dried Fruit: It's healthy, it's easy to carry, and it's satisfying. Taking a bag of trail mix or dried fruit on a plane is a great way to snack without feeling guilty. It's also a great thing to bring along if you have kids. It will keep them busy while forcing them to eat well. However, because salt can contribute to jet lag, it's a good idea to purchase unsalted or low-sodium trail mix.
Crackers: Sure, the stewards and stewardesses will probably give you a bag of crackers during flight, but those bags contain about three crackers and a whole lot of air. Instead of relying on them to feed you, simply feed yourself and bring a box of crackers in your carry-on. These can hold you over until you eat a decent meal, and they can also help you to ward of things like airsickness.
Bagels: Skipping breakfast and getting on a morning flight is a great way to find yourself starving at 30,000 feet. Instead of not eating, or eating something loaded with fat and preservatives, board the plane with a bagel. Many airports are loaded with bakeries, so if you don't bring one from home, it should be relatively easy to find one before your flight takes off.
Bottled Water: No one wants to be that person who has to keep getting up to use the bathroom, but drinking enough water on a flight will help keep you from feeling lethargic when the flight ends. Instead of relying on the airline staff to give you a bottle of water — as their bottles are generally as small as possible — buy your own bottle and drink liberally during the flight. If you are worried about the bathroom thing, simply request an aisle seat.
There are a million and eight things that make flying uncomfortable, but being hungry will compound the discomfort dramatically. Plan ahead and pack food that is easy to carry and easy to eat (boarding a plane with a plate of crab legs is probably not the best idea). Staying full during flight is the first step in making your ride as least turbulent as possible.