How Endurance Athletes Should Carb Up During Workouts

Lori Russell, MS RD CSSD
by Lori Russell, MS RD CSSD
Share it:
How Endurance Athletes Should Carb Up During Workouts

You’ve heard it before and you’ll hear it again: Carbs help boost performance. But how much do they really help and which ones should you be choosing?

Standard nutrition guidelines tell us to consume 45–60 grams of carbohydrates per hour when workouts go beyond 90 minutes. Following this advice helps the body have enough carbohydrates to use for energy during these sessions to avoid bonking. Whether you need 45 grams or 60 grams each hour largely depends on the duration of your training and what your stomach can tolerate during that training. Shorter sessions and lower overall volume can be adequately fueled by fewer carbs, while longer and higher volume workouts need additional fuel. If you’re doing longer training, it will be helpful to your performance to train your gut to take in additional fuel. Those competing in ultra-endurance events lasting more than 3 hours can benefit from going above that range and taking in 90 grams of carbohydrates per hour.


That advice is sound, but what does it actually mean? Let’s explore what 45 grams of carbohydrates equates to and the best sources to fuel your training efforts. Make sure to check your nutrition labels as brands of drink mixes, bars, gels, etc., vary greatly.

Examples of roughly 45 grams of carbohydrates:

  • 1 slice of toast + 1 tablespoon jam
  • 1 sweet potato + 1 tablespoon brown sugar
  • 1 sleeve of energy chews
  • 2 Honey Stinger waffles
  • 2 sport gels
  • 1/2 cup oats + 1 tablespoon maple syrup
  • 3 medjool dates

Examples of roughly 60 grams of carbohydrates:

  • 3 gels
  • 3 Kashi breakfast bars
  • 2 bananas
  • 2 cups of corn flakes with 1/2 cup milk
  • 30 gummie bears
  • 2 Picky Bars
  • 6 servings of Scratch Labs hydration mix


While many foods contain mixed macronutrients, to best fuel your workout, aim to pick foods with most of their calories (if not all) coming from carbohydrates, as that supplies the energy needed to perform. When competing in super long ultra-endurance events, however, mixed nutrients will be more important.

When choosing your carbohydrates, focus on what you can tolerate well. Studies show mixed sugar sources, such as honey, which is a blend of fructose and glucose, is tolerated and absorbed better than single sources. Many athletes assume simple carbs, such as white toast or a sport gel, are better performance foods, however, research has shown the glycemic index of a food makes no difference in how well its carbohydrates impact performance. Meaning you could choose oats or toast, raisins or gels and still get an energy boost.

The biggest factor in choosing a high versus a low glycemic index source is whether you can tolerate the more fibrous carbs in high glycemic index foods before or during your training. The best advice is to try a variety of carbohydrate-rich foods during your training to find which ones work best for your body. If you’re struggling to fuel your workouts on your own, consult a professional sports dietitian.

Build healthy habits with the Low Carb Meal Plan. Sign up to receive daily tips and registered dietitian-approved recipes tailored to your personal calorie and carb goals. Go to “Plans” in the MyFitnessPal app to try our 28-day Low Carb Meal Plan.

About the Author

Lori Russell, MS RD CSSD
Lori Russell, MS RD CSSD

Lori, MS RD CSSD is an accomplished sports dietitian; she holds a Master’s Degree in Human Nutrition and Certification as a Specialist in Sports Nutrition. As a current professional road cyclist and previous elite marathoner and ultra-runner, Lori knows firsthand that food can enhance or diminish performance gains. She understands the importance of balancing a quality whole food based diet with science-backed performance nutrition and strives to share this message with others. Learn more about her @HungryForResults.


Never Miss a Post!

Turn on MyFitnessPal desktop notifications and stay up to date on the latest health and fitness advice.


Click the 'Allow' Button Above


You're all set.