The Runners Guide to Fueling for Long Runs

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Learn how to fuel long training runs so you’re properly nourished on race day.

By Tamar Kane (Reviewed by Natalie Rizzo, MS, RD)

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If you’re a runner, you’ve probably heard people discuss their long-run fueling plan. Some people swear by pre-run oatmeal, others love gels during the run, and some swear by sports drinks to keep them energized.

But you have to figure out what works best for you to make it through the long run and feel good! Just as you might try out a pair of socks on a long run before deciding to wear them on race day, you should also test out your fueling plan.

So how exactly should you be fueling for those long runs?  This article provides all the info you need to know on what to eat before, during and after a long run, as well as timing of fuel and potential stomach issues and how to handle them.

marathon race

Why do you need to fuel during a long run?

When you run, your body relies on two forms of carbs for fuel– dietary carbs and glycogen (aka stored carbohydrates).

Glycogen is metabolized for energy during the first 30-60 minutes of running. After that, the body uses carbs from a recent meal that might be floating around in the body. That’s why eating carbs before a run is incredibly important.

What to eat before a long run

While pre-run fueling differs for each person, the general rule is to consume about 1 to 4 grams of carbohydrates per kilogram (0.4-1.8 grams of carbohydrates per pound) of body weight 1 to 4 hours before running. Obviously, that’s a very wide range of fuel.

For example, a 150-pound runner may need anywhere from 60-270 grams of carbs before a long run. If you’re eating a few hours before a training run, consume a complete meal with carbs, protein, and fat.

You’ll likely be on the higher end of the range, especially if your run is in the double digit mile length. The further out you are from your run, the larger the meal you can consume.

One hour before your run, aim to consume easy-to-digest carbohydrates, while keeping protein, fat, and fiber content low to avoid stomach upset. For example, the 150-pound runner may eat 1 slice of toast (13 g) with 2 tablespoons of peanut butter (7 g), 1 banana (27 g), and 1 tablespoon of honey (17 g). Some smaller carb-rich foods include fresh or dried fruit, pretzels, white bread, or a bar.  

runner on pavement

Finally, make sure to hydrate before your runs to prevent dehydration. Starting runs in a dehydrated state can negatively impact performance and make it feel like you are working extra hard!

While you should be hydrating with water, note that if you are a coffee drinker, you might feel encouraged by the fact that research has shown caffeine may benefit performance. However, if you do not typically drink coffee before running, marathon training runs are not the ideal time to start, as caffeine can cause an upset stomach.

What to eat during a long run

If you’ve ever gone on a long run without fueling properly, you are likely familiar with the fatigue, brain fog, and heavy legs that can set in. Indeed, this occurs because glycogen stores and dietary carbs are depleted after about 60-90 minutes of endurance activity.

For runs that are longer than one hour, aim to consume around 30-60 grams of carbohydrates per hour. For runs over 2.5 hours, it is recommended to consume around 60 grams of carbohydrates per hour. Some popular options include:

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I’m Natalie Rizzo, an NYC-based Registered Dietitian.

My mission is to help everyday athletes fuel their fitness with plants.

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