Trail Running 101: How to Fuel a Trail Run

Trail Running 101: How to Fuel a Trail Run, BLISTER

In our Trail Running 101 series, we’re covering just about everything you might want to know to get started in the sport, as well as tips and tricks for experienced runners to make it more enjoyable. This is the sixth part of the series — stay tuned for more.


Learning to eat on the run can be one of the most enjoyable — and challenging — parts of trail running. Unlike shorter outings, trail runs of an hour or more usually require fueling along the way, not just before and after. The good news is there are all types of fun ways to fuel (hello, frosting and pizza!). The bad news is sometimes it takes practice to figure out what works with your system and what doesn’t. Every runner is unique, so there’s no one-size-fits-all optimum way to fuel a trail run. But here are some basics to get started.

Trail Running 101: How to Fuel a Trail Run, BLISTER

Before the run

You don’t want to head out on a run in a caloric deficit — that’s a recipe for bonking / losing your energy. Instead, make sure to have balanced blood sugar and good glycogen stores beforehand. That means you’ve had a balanced meal or snack a couple hours before your run. Some runners also like to top off right before heading out, but the key is not to overfill your stomach. Focus on simple, easy-to-digest options like a banana with peanut butter, an energy bar, or yogurt with granola. Avoid large amounts of simple sugars, like candy and other processed sweets, which can draw water to your gut and cause digestive distress.

During the run

For a run shorter than an hour, you should be able to get away with just hydrating. But the human body can’t store carbs to supply exertion like that for more than about 90 minutes. So if you’re planning to run much more than an hour, you’ll want to pack calories to keep you going. This is where a running vest or handheld water bottle with a pocket comes in handy. Refueling every 20 to 30 minutes will help keep your energy up, and you’ll want to have your snacks easily accessible.

You don’t have to keep running while you eat if you don’t want to. While some foods — like gels and chews — are easier to literally eat on the go, you might find it easier to just take a break for a quick snack or practice eating while you walk. Focus on small bites and chewing well before swallowing — no one needs a Clif Blok lodged in their throat in the backcountry. The more you try eating while moving, the easier it gets, and pretty soon you might find yourself still jogging along when you decide to pull a snack from your vest pocket.

Trail Running 101: How to Fuel a Trail Run, BLISTER
Photo by Tony DiPasquale

The key to these mini snacks is to keep feeding yourself a continuous, light stream of easy-to-digest, carb-focused calories at regular intervals. Think somewhere in the 75 to 150 calorie range. If you’ll be running for several hours, it might be smart to start mixing in some fat and protein, too. (Ultrarunners have been known to pack pizza slices, potato chips, and even cake frosting for fuel on the go.) But for the first couple hours, foods like gummy chews or gels work great. Some other good options include bananas, cooked potatoes, date and coconut balls, rice balls, and peanut butter and jelly. Just make sure to pay attention to how much fiber you’re ingesting, since too much can cause digestive distress.

One additional thing to think about: electrolytes. Again, a good rule of thumb is that if you’re running longer than an hour, you’ll be sweating out enough electrolytes (crucial minerals like sodium, potassium, calcium, and magnesium) that you’ll need to replace them as you go. Some sport chews and gels include electrolytes in their recipe, and so do many sports drinks. So as you’re fueling yourself through the run, make sure to pay attention to electrolytes as well.

After the run

Congratulations, you made it through your long trail run! Now it’s time to catch up on calories and hydration. Think water, protein, and maybe electrolytes, too. One reason to carry plenty of water on your run is that it can take a while to catch up on hydration once you get dehydrated. The average person can only absorb about a liter of water an hour, so even if you come home and slam multiple liters, it won’t do you much good if you let yourself dip too far into the dehydration zone. If you do feel dehydrated when you’re done, sipping water continually for multiple hours can help you catch up.

You can typically replace missing electrolytes by eating regular foods. Many sport drinks and mixes offer specifically balanced amounts of sodium, calcium, potassium, and magnesium, but sodium is still by far the highest ingredient, and salty snacks like chips and nuts have plenty of it. And finally, for repairing muscle tissue you broke down during your run, focus on protein, like eggs, beans, veggies, fish, and lean meats.

Trail Running 101: How to Fuel a Trail Run, BLISTER

Experimenting with different types of running snacks and recovery foods can be really rewarding. Pay attention to what goes down easily and doesn’t disturb digestion. And one word of advice: if you have a big race or run that’s important to you, stick with the snacks you know work for you — don’t experiment with something new at the last minute. Just like with other parts of running, practice makes perfect.

Check out the rest of our Trail Running 101 series

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