The short answer is yes, absolutely, runners do need more calories. But let’s dive in and talk through how specific nutrition requirements can greatly impact performance in training and ultimately, on race day.

It’s estimated that runners burn over 100 calories per mile of running. This, of course, will vary in how efficient and fit you are as a runner. Regardless, if you’re running 5+ miles as a long-distance runner or triathlete, this number can start to add up quickly.

But, it’s not just about the calories you burn during your run. It’s also about the calories needed to effectively and efficiently recover from that run. And that’s why we often see athletes under-fueled because they don’t factor this in.

The Consequences of Under fueling

Under-fueling as a runner can lead to a decrease in performance during your events, low energy levels throughout the day, an epic uncontrolled appetite (including cravings), and chronic fatigue.

For many athletes, they know they need to fuel more, but they’re worried about weight gain. I get it. But being strong and well-fueled will always perform well than under-fueled and skinny (and you’ll be happier and less injury prone as well!). If you’re concerned about weight gain, start small and gradual by increasing your calorie and fuel intake. That will allow your body to adjust and hopefully not see the scale fluctuate as much.

Why runners need calories (and carbs)!

Calories, especially in the form of carbohydrates, get stored as glycogen in your muscles. Your body uses this stored glycogen as energy to continue to perform at your desired pace. The higher the effort, the faster the use of glycogen.

With fully loaded glycogen stores, athletes usually have about 90-120 minutes of adequate energy levels before energy levels start dipping.

When you aren’t eating enough and then running long distances, your glycogen stores are smaller and you run out of energy faster!

You’ll usually start to feel fatigued and weakness. Eventually, you may end up “hitting the wall” and your body is going to have nothing left to continue at your desired pace.

Don’t make the mistake of under-fueling as an endurance athlete. There are plenty of strategies you can use to stay on top of your fueling such as carb loading and meal prepping.

If you need help with your carb loading, check out my carb loading guide for endurance athletes!

The Takeaway

Knowing what and how much to eat may seem complicated or overwhelming as an athlete. Especially when you have specific, performance-related goals.

But the good news for you is that you don’t have to do this alone! My dietitian team and I specialize in helping runners and triathletes with their nutrition through a flexible eating style. Learn more here through my services page.

Want to binge more runners’ nutrition content? Head over to this article on 3 key nutrition tips for endurance running!