Nutrition Basics for Trail Running

There are a few lucky runners out there with stomachs made of steel who can handle just about any food at any time. But for the rest of us, paying attention to what we eat and when we eat it can be the difference between a good run or a miserable one.

When do you need a nutrition plan? For an easy run lasting about an hour or less, most people can get by with a bit of water and maybe an energy gel or two. But when you run for longer than that, and especially when you’re out for more than three to four hours, having a plan for exactly what and when you eat becomes increasingly important.

It’s not always simple to figure out how to best fuel up before, during and after a run. If you ask five trail runners how they do it, you’ll probably get five different answers. To really discover what works for your body, you’ll need to get out there and experiment. This article focuses on three areas that will help you on your way:

  • Nutrition basics: Learn where your body draws energy from and what it needs to stay strong during a run.

  • Making a nutrition plan: What you eat before, during and after a run can greatly affect your performance on the trail.

  • Nutrition tips: Following a few simple tips can help you find what food works for you and stay fueled up during a run.


The Basics of Nutrition for Trail Running

So, you’re probably wondering, “How much should I eat while running?”

The quick answer is that 200–300 calories per hour is a good ballpark figure to shoot for. That said, the exact number of calories depends on several factors, including the length and intensity of your run and your body type: A larger person will likely need more calories per hour than a smaller person. Likewise, someone doing a very strenuous run will need more calories per hour than someone doing a short, easy run.

Also, the quality of your calories—the type of food you eat—is key:


guide for how many calories and carbs to consumer on a trail run up to 3 hours in length

The Role of Carbohydrates

When you run long distances, your body relies initially on glycogen as its primary fuel. Glycogen is stored in the muscles and liver for easily accessible, efficient energy.

Glycogen is derived from eating carbohydrates. This is why you’ve probably heard of athletes who will “carbo load” the night before a big run. Eating lots of carbohydrates like pasta, bread or potatoes helps fill up your glycogen stores to ensure you start your run with a full tank of energy.

Your body burns through glycogen relatively quickly (it can be spent within a couple of hours) so you need to replenish your glycogen stores with mid-run snacks, like energy bars, gels and chews that contain carbohydrates.

Know that your body can only process about 60 grams of carbohydrates per hour. Eating more than that can put you at risk of an upset stomach.



guide for how many calories, carbs, and protein to consume when on a trail run longer than 3 hours

The Roles of Protein and Fat

When your run hits the three- or four-hour mark, your body will turn to slow-burning fat and protein for energy. To keep your energy stores steady for the long haul, you’ll want to eat some fat and protein while you’re running. A good strategy is to replace about a quarter of your carbohydrate calories with protein. Your hourly caloric intake can remain in the same 200–300 range.

Eating fat and protein not only gives your body a long-lasting energy source, it can also provide your taste buds with some relief from the monotony of energy gels. Mixing in solid foods like bars, wafers or PB&J sandwiches can be a welcome change.


Making a Nutrition Plan

a trail runner displaying three edible bar options

Every runner is different so it’s difficult to say exactly what you should eat and when to eat it but there are some reliable guidelines to get you started. You’ll need to experiment with foods during training runs to see what actually works for you. And, always remember: Despite what anyone tells you, if it works for you, keep on doing it.


When to eat

Types of food


Night before

High carbs; low fiber, fat and protein

Fresh fruits and vegetables
Lean meat

Morning (2 hrs. before)

Mostly carbs; a little protein OK

Granola with berries
Bagel with peanut butter
Oatmeal with dried fruit

During run, under 4 hrs.

Easily digested carbs and sugars

Energy gels
Energy chews
Fresh fruit

During run, after 4 hrs.

Mostly carbs; add some protein

Energy bars
Nut butters
Beef jerky
Drink mixes that include protein

After the run

Foods high in protein; hydrate with electrolytes

Lean meats
Fresh vegetables

The Night Before a Long Run

Eat a healthy meal that’s high in carbohydrates but low in fiber, fat and protein. The fat that you do eat should be healthy fat that you get from foods like avocados, coconut oil and extra virgin olive oil. Healthy fats are good for heart health, immune system function, joint health, recovery and injury prevention. Don’t overdo it and eat a huge meal that will leave you feeling full the next morning. Also, avoid foods that you know will cause you issues. For example, if spicy foods irritate your stomach, stay away.


The Morning of a Long Run

Your pre-run meal should be made up mostly of carbohydrates. Including some protein can help keep you satiated during the run, but don’t eat too much fat or fiber as these can leave you feeling full and bloated. Granola with berries, a bagel with peanut butter, or oatmeal and dried fruit or bananas are good ideas. Generally, shoot for a meal that’s about 400–600 calories.

It’s important to give your body time to digest your pre-run meal. You can experiment with this a bit, but try eating at least two hours before your run.  Some people find that a light snack closer to the start of their run is OK.


During a Long Run

If your run will last less than four hours, you can probably get by with eating energy gels, chews and fruit that deliver easily digested carbohydrates and sugars. If your run will stretch past the four-hour mark you’ll want to mix in some protein for sustained energy. Energy bars, nuts, nut butters, beef jerky, or drink mixes that include protein are all good options. Also, listen to your cravings. Your body does a surprisingly good job of telling you what it needs.

Remember to shoot for 200–300 calories per hour. Many pre-packaged energy gels, bars and chews come in portion sizes that make this simple to do.


After a Long Run

Eat a healthy meal with good nutritious ingredients within one hour of finishing your run to replenish all that you burned through. Foods high in protein are great for helping your body rebuild tissues and recover after exercise/activity. 

Don’t forget to hydrate: Drink an electrolyte replacement drink to replace the sodium and potassium that you lost while running. It’s OK to celebrate after a big run with a beer or two, but go easy. Alcohol is a diuretic, which means it can pull fluids from your body, making you more dehydrated. Learn more about hydration in our article, Hydration Basics for Trail Running.



Nutrition Tips

a trail runner enjoying some running goo
Trial and error: Figuring out what foods work for your individual body while running requires some experimentation. Some lucky runners can handle any and all foods, but many others find that the jostling of running brings on nausea and irritation. If you experience stomach discomfort, check out the nutritional labels on food products and try avoiding common allergens like whey, gluten or soy. You can also try cutting out solid foods and see how sports drinks, shakes and homemade smoothies feel.

Experiment with different food combinations and quantities before, during and after your training runs to narrow down what works and what doesn’t. Using a journal to keep track of what you eat and when can be helpful.

Drink your calories: If you know that solid foods irritate your stomach while running, you can try getting your nutrition in liquid form. Many sport drinks include calories in the form of carbohydrates, fat and protein. However, be careful not to overdo it and combine an energy drink with energy food—too many carbs can cause an upset stomach. If you're using energy gels, chews or bars for nutrition, follow up a bite with a swig of straight water rather than a sport drink.

Train the way you race. Race the way you train: If you’re signed up for a big trail race, use your training runs to figure out what foods work for you and then practice eating the way you will on race day.

When race day arrives, don’t suddenly try something new. It can be tempting to scarf down goodies from the spread of food at an aid station, but if you don’t know that candy bars, carbonated drinks or any of the other offerings work for you, then don’t eat them. You’ve developed a plan, so stick to it.

Set a timer: It’s easy to zone out on a long run and lose track of the last time you had a sip of water or sucked down an energy gel. Many runners like to set a timer on their watch to sound an alarm every 20–30 minutes as a reminder to eat and/or drink 80–100 calories. 



Nutrition Basics for Trail Running pinterest infographic




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Contributing Experts

Julia Zuniga
Julia Zuniga

Julia Zuniga is an REI Outdoor School Instructor in San Diego, Calif. She holds a Master’s Degree in Exercise Science and her expertise is in fitness and trail running.

Cory Rand
Cory Rand

Cory Rand is an REI Outdoor School Instructor in Washington D.C. He's an avid runner who races half marathons, full marathons and ultramarathons on roads and trails.