To avoid running out of energy – or “bonking” – on a long trail run, eat and drink as you go.
Size up the trail before you go. If it's exceptionally long or challenging, you should make eating and drinking as you run a major priority.
Prepare before your run. Drink at least a liter of water and snack on high-carbohydrate foods like fruit and energy bars up to 2 hours before you run. Sip a cup or two of water right before you hit the trail.
Carry water on your run. Try holding a small water bottle in your hand or stashing it in a hiker's fanny pack. A lightweight backpack hydration system can prove handy on very long runs.
Carry food. Energy bars can be tucked into pockets or into the same fanny pack or hydration backpack that holds your water.
Sip water as you run, before you become thirsty. Drink every time you're on an easy section of trail or stop to rest. Drink more water during strenuous runs and on runs at high altitudes.
Try not to drink or eat while running on difficult sections of trail, such as rocky or wet sections, or places where roots stick out of the ground. Instead, stop running, run in place or wait until you reach an easy section where you're not likely to trip.
Nibble at food such as energy bars or dried fruit every 15 minutes or so. Chew thoroughly to avoid choking and to aid in the digestion process. Think of it as gas for your high-performance, all-terrain, two-legged sports machine.
Continue to drink water and eat water-rich foods such as oranges and apples after your run.