A Nutrition Guide: What to eat on an ultra run?

October 8, 2025 •

4 min read

For some ultrarunners, races exceeding six hours can induce an energy deficit of over 7,000 calories, highlighting the critical importance of a sound fueling strategy to avoid "bonking". A successful plan for what to eat on an ultra run? is not a one-size-fits-all approach, but a personalized and well-practiced nutritional blueprint that evolves with the race.

Quick Summary

This guide provides a comprehensive overview of ultra-run nutrition, covering pre-race carb-loading, race-day fueling with carbohydrates, protein, and fat, and post-race recovery. It details the importance of hydration, electrolyte management, and 'gut training' to prevent gastrointestinal distress. Different fuel options, from engineered products to real food, are explored, along with strategies for effectively utilizing aid stations and adapting to changing conditions.

Key Points

Carbohydrates Are Core: Aim for 60-90 grams of carbohydrates per hour during your ultra to sustain energy and avoid 'bonking'.
Train Your Gut: Practice your race-day nutrition strategy during long training runs to condition your stomach and prevent GI issues.
Hydrate Smartly: Consume 400-800 ml of fluid per hour with 500-700 mg of sodium per liter, adjusting for environmental conditions.
Mix Up Your Fuel: Alternate between engineered products like gels and real foods like potatoes or pretzels to combat flavor fatigue over long distances.
Prioritize Recovery: Within 30-60 minutes post-race, consume a carb-to-protein ratio of 3:1 or 4:1 to kickstart muscle repair and glycogen replenishment.
Don't Try New Things on Race Day: Stick to foods and drinks you have thoroughly tested in training to avoid unwelcome digestive surprises.

The Crucial Role of Carbohydrates

Carbohydrates are the cornerstone of any ultra-running nutrition plan. Your body relies on its limited glycogen stores for quick, efficient energy during intense exercise. Once these stores are depleted, performance can plummet dramatically, a state known as "hitting the wall" or "bonking". A consistent intake of carbohydrates during the race is therefore non-negotiable to maintain a steady energy supply. Elite and recreational runners alike aim for a carbohydrate intake of approximately 60 to 90 grams per hour for events longer than 90 minutes. For some, this can be pushed to 120 grams per hour by utilizing multiple transportable carbs, such as a 2:1 ratio of glucose to fructose, which use different pathways for absorption.

The Importance of 'Gut Training'

Your digestive system needs to be trained just like your muscles. Consuming large amounts of food during exercise diverts blood flow away from the stomach, which can lead to severe gastrointestinal (GI) distress if your gut isn't conditioned to handle it. Practicing your race-day nutrition strategy during long training runs is essential for training your gut to absorb and utilize carbohydrates efficiently. This includes experimenting with the types of food and fluid you plan to consume, mimicking race conditions like time of day, intensity, and temperature. Variety is key, as relying on a single type of fuel (e.g., only sweet gels) can lead to flavor fatigue and nausea over many hours. This is why many ultrarunners incorporate a mix of sweet and savory items.

Race Day Fueling: A Balanced Approach

An ultramarathon is not a sprint, and your nutrition shouldn't be either. A balanced intake of carbohydrates, protein, and fat will provide sustained energy and help manage appetite over long distances. While carbohydrates are the primary fuel, small amounts of protein and fat can be beneficial, especially in races exceeding 8-10 hours. Protein can help reduce muscle breakdown, while fat offers a high-calorie, energy-dense option. Many runners find a mix of engineered sports nutrition products and solid 'real food' works best for them.

Here are some examples of what to include in your race day fueling:

Engineered Fuel: Energy gels, chews, and sports drinks provide quick-acting, easy-to-digest carbohydrates and electrolytes.
Real Food: Small portions of pretzels, boiled potatoes with salt, rice cakes, peanut butter and jelly sandwiches, or candy like gummy bears can offer a change in texture and flavor. Some ultrarunners even use savory options like beef jerky or broth in later stages of a race.
Fluids and Electrolytes: Hydration packs or bottles filled with water and electrolyte drink mix are crucial. The goal is to consume 400-800 ml of fluid per hour, with 500-700 mg of sodium per liter, adjusted for individual sweat rate and climate.

A Tale of Two Fueling Strategies


Feature	Engineered Sports Fuel Approach	Real Food / Hybrid Approach
Carb Source	Maltodextrin, fructose, glucose blends in gels, drinks, chews.	Potatoes, rice, dates, honey, candy, sandwiches.
Ease of Digestion	Designed for rapid absorption and minimal GI distress when used correctly.	Can cause stomach upset if not practiced, but often more satisfying psychologically.
Caloric Density	Concentrated source of calories per unit of weight; easy to carry.	More bulky and heavier; can feel more substantial and satisfying.
Flavor Profile	Often limited to sweet flavors, leading to palate fatigue over long events.	Offers a wide variety of sweet, salty, and savory options to combat flavor fatigue.
Logistics	Less messy and easier to consume on the move, especially on technical terrain.	Can be harder to chew and swallow while running, but great for slower hiking sections.
Electrolytes	Often contain sodium and other electrolytes, though amounts vary significantly.	Requires supplementing with salt pills or electrolyte drinks to meet needs.

The All-Important Recovery

After crossing the finish line, your nutritional job isn't over. Immediate recovery is essential to replenish depleted glycogen stores and begin muscle repair. The "anabolic window" in the first 30-60 minutes post-race is when muscles are most receptive to nutrients. Aim for a meal or snack with a 3:1 or 4:1 carbohydrate-to-protein ratio. Examples include chocolate milk, a smoothie with protein powder, or a sandwich with lean protein. Continuing to rehydrate with electrolyte-rich fluids is also critical, especially if you lost significant fluids during the race. The following days should focus on balanced meals rich in complex carbs, lean protein, and healthy fats to support your body's continued recovery process. For additional expert guidance, consulting a certified sports dietitian is always a wise investment.

Conclusion

Successfully navigating an ultra run requires a nutrition plan as carefully considered as your training. By prioritizing carbohydrates, training your gut, and balancing engineered and real food options, you can build a personalized strategy that works for you. Remember that hydration and electrolytes are just as important as calories. A well-executed fueling plan is often the difference between finishing strong and a DNF (Did Not Finish), so practice what you plan to do on race day. Listening to your body, adapting to conditions, and focusing on recovery will set you up for long-term endurance success.

Frequently Asked Questions

To prevent flavor fatigue, alternate between sweet and savory foods. A variety of textures and tastes, including options from both engineered products and real foods like salty potatoes or broth, can keep your palate from tiring of one flavor.

Most ultra runners use a combination of a hydration vest with front pockets for easy access to gels, chews, and small snacks. Some races also allow drop bags, which you can pack with extra fuel and supplies to be accessed at designated aid stations.

There is no single 'better' option, as most ultrarunners use a hybrid approach. Engineered gels offer rapid, concentrated carbs, while real food can feel more substantial and help combat flavor fatigue. The best strategy is to train with both to see what your gut tolerates best.

In hot or humid conditions, your sweat rate and electrolyte loss increase. You will need to increase your fluid intake towards the upper end of the recommended 400-800 ml per hour and potentially consume more sodium, aiming for 600-1000 mg per liter of fluid.

It is not recommended to rely on aid station food exclusively if you haven't tested similar options during training. While aid stations can offer variety, trying unfamiliar foods on race day significantly increases the risk of stomach upset.

Your pre-race meal should consist primarily of carbohydrates and be easily digestible. Stick to meals you have practiced with during training, such as oatmeal, toast with jam, or rice. Eat 2-3 hours before the race to allow for proper digestion.

Focus on a combination of carbohydrates and protein immediately after the race to begin muscle repair. Good options include chocolate milk, a recovery smoothie with protein powder, or a balanced meal with rice, chicken, and vegetables.