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Fueling For An Ultra Vs Marathon

Fueling For An Ultra Vs Marathon Jackie Hendrickson Run Tri Bike Contributor

Practicing optimal fueling strategies is a fundamental component of any marathoner or ultra-marathoner’s preparation for their race. Even the best trained athlete can be affected by side stitches, low blood sugar, or nausea on race day. Learning to fuel properly can help you perform at your very best & enjoy your experience on the roads or the trails. This means knowing how long you’ll be performing as there is a difference when fueling for an ultra vs a marathon.

Fueling strategies for an ultra-marathon vs. a marathon depend greatly on one aspect: time on your feet. Regardless of the terrain you are competing on, the time spent on your feet is the most important aspect of which fueling strategy you choose to rely on.

In basic principle, the longer time you spend on your feet, the more carbohydrates per hour you need to consume in order to achieve optimal performance. Here’s a general guideline:

Carbohydrate Guidelines Per Hour For Endurance Athletes

<60 minutes → no fuel required
1 hr – 2 hr → aim for 30-60 grams of carbohydrate per hour
2 hr – 3 hr → aim for 60 grams of carbohydrate per hour
3 hr – 5 hr → aim for 60-90 grams of carbohydrate per hour
5 hrs + → aim for 90 (up to 120) grams of carbohydrate per hour

If these numbers intimidate you, you are not alone! It takes time, practice, and patience to get your body used to fueling at this level. Experiment with various fueling products to find which options feel best in your body specifically.

Specific Fueling Options

When aiming to achieve higher amounts of carbohydrate (60+ grams per hour), many athletes find it helpful to consume a variety of gels, chews, and high-carbohydrate/electrolyte beverages in order to get enough fuel in without experiencing “palate fatigue” (aka a lack of desire to eat one particular food because you’ve consumed so much of it). Some of my favorite carbohydrate-rich products include Spring Awesome Sauce gel, Spring Canaberry gel, Honey Stinger chews, Clif Shot Bloks, Tailwind Hydration packets, and Maurten gels & beverages.

Athletes participating in longer, ultra-endurance events (4+ hours) are more likely to handle a greater variety of foods than those at racing for less time at a higher intensity. The more your body is working, the more sensitive your stomach (is likely) to be. You may see food options such as roasted potatoes, peanut butter and honey sandwiches, pancakes, clif bars, or breakfast burritos at races longer than a marathon. These foods can also be excellent choices for fueling in these scenarios; providing the gut with more familiar foods with additional nutrients beyond carbohydrate (fat and a little protein) can be helpful for many athletes who are on their feet for periods of time longer than 5 hours. In this case, I prefer to use a “calories per hour” approach versus a “carbohydrate per hour” approach to avoid feelings of over-fullness.

Calories Per Hour Recommendation For Ultra-Endurance Athletes

<5 hours → use carbohydrate per hour approach
5 hrs + → aim for 360-480 calories per hour (most of this should still be carbohydrate, but adding a little bit of fat or protein, such as olive oil on roasted potatoes or peanut butter on a bagel, is appropriate)

Planning It All Out

So how do you put it all together? Using the table below, I like to plan out my nutrition for key workouts and races by breaking it up into 1 hour blocks. Using the “per hour” recommendations for carbohydrate, sodium, and hydration, I can then figure out how to meet that recommendation with the fuel I choose to use on any given day. Here is a real life example of a fueling plan a client and I created for a 15 mile long run using products they preferred:

Date: October 8th or 9th
Time of day: Morning
Type of workout/race: 15 mile long run

Pre-run fuel

  • 1 cup coffee (as you normally would)
  • Toast with almond butter OR picky bar
Hour 1 Hour 2 Hour 3
Carbs 50 grams/hr
1 scoop. Tailwind in 12 oz water (sip throughout) 30 minutes: honey stinger gel
1 scoop. Tailwind in 12 oz water (sip throughout) 90 minutes: honey stinger gel
Optional gel at 2 hr mark. If you have more than 3 miles left, take it.
Sodium 250-300 mg/hr (general rec’d are 300-600 mg/hr)
155 mg (Tailwind) 50 mg (honey stinger gel) 50-100 mg (1-2 Salt Stick salt tabs depending on how hot it is) Total sodium: 255-305 mg
155 mg (Tailwind) 50 mg (honey stinger gel) 50-100 mg (1-2 Salt Stick salt tabs depending on how hot it is) Total sodium: 255-305 mg
If going to 2 hrs 30 min, 50-100 mg (1-2 Salt Stick salt tabs) 50 mg (honey stinger gel) Total sodium: 50-150 mg
Hydration (generally 12-24 oz. per hour is rec’d)
12 oz of Tailwind
12 oz of Tailwind
If you have somewhere to fill up your bottle, another 4ish oz could be helpful


Fueling for any long distance event requires practice, experimentation, and patience to find your perfect plan. Using carbohydrate or calorie based guidelines based on the time you will be spending on your feet is the main difference to be attentive of when practicing fueling strategies for varying distances. For the most part, switching to a calorie-based approach is most helpful when racing or training for longer than 5 hours at a low intensity. Plan out your fueling plan beforehand so that you can know ahead of time what to pack & have a documented version of what you have done so that you can improve on it in the future.

Happy Fueling!

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Jackie Hendrickson RD, MPH Enduura Nutrition Run Tri Bike Magazine Tips

Jackie Hendrickson RD, MPH is a registered dietitian with a Masters Degree in public health nutrition from Utah State University. Jackie is the owner of Enduura Nutrition and loves coaching her athletes to their athletic potential through sustainable training & nutrition principles. She is an avid road & trail marathoner with a background in collegiate track, cross country, and competitive swimming. Jackie and her husband, Adam, were teammates in college and continue to pursue their running goals together. They live in beautiful Ogden, Utah with their 2 year old son, Lincoln.