Choose the best: Select a gel that has 25 to 30 grams of carbohydrates from sources such as honey, brown rice syrup or maltodextrin, and 50 mg of sodium per packet. Some brands such as e-Gel pump up the electrolytes (sodium and potassium), which you may need on long or intense runs.
Check the label for caffeine. British researchers found caffeine stimulates the central nervous system and brain, making exercise seem easier and allowing athletes to feel as if they can exercise longer. If you're not used to it, though, caffeine can make you jittery, Clark says.
Keep in mind: Gel packages can become a sticky mess when you use them, and you have to drink water each time you down one. Try a variety of gels during training to find one that agrees with you.
How to use them: How much gel you need depends on variables such as your weight and running intensity. Clark recommends one gel for every 30 to 40 minutes of running, starting during the first hour. It's essential to drink 16 ounces of water for every gel consumed.
Great as pre-run or post-run snacks, you can eat bars during a run, too.
Why they work: Bars such as CLIF Bar and PowerBar are jam-packed with carbohydrates and are better than drinks and gels at satisfying hunger during long runs.
Choose the best: Select bars with 40 grams or more of carbohydrates, from ingredients such as dates or brown rice syrup, and small amounts of fat, protein and fiber.
Keep in mind: Bars with too much fat, protein and fiber can delay digestion. Choose a bar that has 200 to 250 calories with about 5 grams of fiber, 5 grams of fat and 10 grams of protein. Bars can also be challenging to eat when running, and you must drink water with them.
How to use them: Consume one bar for every hour you run. Break bars into equal-sized pieces prior to a run and eat them at regular intervals throughout exercise. Drink 4 to 8 ounces of water every 15 minutes when eating bars.
Bite-size chews punch up your energy like a jolt of coffee.
Why they work: GU Chomps, LUNA Moons, CLIF Shot Blocks and other chews come in bite-sized pieces and pack in the same carbs found in drinks and gels. Because of the smaller caloric content, chews can be easier to digest than bars or gels.
Choose the best: Look for chews with about 5 grams of carbohydrate and 10 mg or more sodium per chew.
Keep in mind: Like gels and bars, drink water each time you pop one in your mouth. Chew them well to reduce choking risk.
How to use them: Five grams of sugar per chew means you need to consume at least six per hour of running. Drink 4 to 8 ounces of water every 15 minutes.
Many of the performance advantages of engineered sport products are found in food in your fridge or pantry.
Why they work: Some natural foods contain the right ratio of carbs to aid long-distance runners.
Choose the best: "Stick with high-carb, sugary options with less fat and protein, such as dried fruits, honey, Fig Newtons, Twizzlers or gummy bears," Clark says.
Keep in mind: Fruit contains fructose, which can cause stomach distress, and you still need to drink plenty of water--16 to 32 ounces per hour--to stay hydrated. If the food lacks sodium, add about 1/4 teaspoon salt per quart of water.
How to use them: To determine how much of a food you need to consume during a run, read the label or visit a site like nutritiondata.com. For example, an ounce of dried apricots has 6 grams of carbs, so you need at least 5 ounces every hour to reach 30 grams of carbohydrate intake.