What to eat during 50K ultra?

Ultrarunners can burn between 600 to 1,000 calories per hour, but the body can only absorb roughly 200-300 calories hourly while running. To successfully manage this energy deficit and finish strong, understanding what to eat during a 50K ultra is the single most important component after your training is complete.

Quick Summary

A comprehensive 50K fueling strategy must include balanced intake of energy gels, real food, and a consistent electrolyte plan. Practicing your nutrition and hydration consistently during training is paramount to avoid gastrointestinal distress and maintain steady energy on race day.

Key Points

• Start Fueling Early: Begin consuming calories 30-45 minutes into the race and continue every 15-30 minutes to prevent glycogen depletion.

• Embrace Food Variety: Mix sweet gels and liquid carbs with savory 'real food' like salted potatoes or pretzels to prevent flavor fatigue.

• Train Your Gut: Practice your race-day nutrition plan during long training runs to acclimate your digestive system and prevent mid-race GI issues.

• Prioritize Electrolytes: Beyond water, consume electrolyte-rich drinks or salt capsules to replace sodium lost through sweat and prevent cramping.

• Strategize Aid Station Use: Don't rely solely on race provisions; carry your own tested fuel and use aid stations to supplement and top off.

• Carb-Load Smartly: Increase easy-to-digest carbs in the 2-3 days before the race, but avoid overstuffing yourself with high-fiber foods.

The Fundamentals of 50K Fueling

Unlike a standard road marathon, a 50K ultramarathon often takes runners longer to complete, involves different terrain, and is typically run at a lower intensity. This changes your fueling strategy significantly. While a marathon pace may favor simpler carbohydrates like gels, the sustained duration of a 50K often requires a wider variety of fuel sources to prevent flavor fatigue and provide sustained energy. A successful ultra runner must become a master of their nutrition just as much as their training.

The 3 Golden Rules of Ultra Nutrition

1. Eat Early, Eat Often: Don't wait until you're hungry or low on energy. Start fueling within the first 30-45 minutes and continue with small, frequent doses of calories every 15-30 minutes. This helps maintain stable blood sugar levels and prevents the dreaded 'bonk'.
2. Variety is Key: Your stomach will eventually protest against continuous sweet gels. Mix in savory real foods and different carbohydrate sources to keep your taste buds and gut happy. Salty snacks can also help replenish electrolytes.
3. Nothing New on Race Day: The golden rule of endurance sports. Practice your exact race-day nutrition plan—including all foods, gels, and drinks—during your longest training runs. This 'gut training' prepares your digestive system for race-day stress and minimizes the risk of stomach issues.

What to Eat During the Race

Your 50K nutrition plan should incorporate a mix of liquid and solid calories. Aim for 200-250 calories and 30-60 grams of carbohydrates per hour, adjusting based on body size, intensity, and conditions. After about four hours, consider incorporating a small amount of protein and fat to help maintain energy levels.

Liquid Calories:

• Carb-Electrolyte Mixes: Products like Tailwind, Skratch Labs, or Maurten Hydrogel are designed to provide both hydration and calories in an easy-to-digest liquid form, killing two birds with one stone.
• Energy Drinks: Cola or ginger ale can offer a quick sugar and caffeine boost late in the race, though they should be used sparingly.

Packaged Foods:

• Energy Gels & Chews: These provide a fast-acting and highly portable source of carbohydrates. A variety of brands (GU, CLIF Bloks, Maurten) offer different textures and flavors.
• Energy Bars: Options like Näak Ultra Energy Bars or Maurten Solid bars provide more substantial, slower-burning fuel.

'Real Food' Options:

• Salty Potatoes: Boiled, salted potatoes are a simple, carbohydrate-rich, and easy-to-digest option that also provides crucial sodium.
• Rice Balls: The Japanese favorite, onigiri, or simple rice balls with a touch of miso, offer sustained energy.
• Fruit: Bananas are a classic ultra food, providing potassium and simple carbs. Watermelon and oranges are great at aid stations.
• Salted Pretzels/Chips: These are perfect for satisfying a salt craving and providing simple carbs.
• PB&J Sandwiches: Cut into small, manageable pieces, these offer a balanced mix of carbs, protein, and fat.

Real Food vs. Gels: A Comparison

Feature	Real Food (e.g., potatoes, wraps)	Gels & Chews	Liquid Carbs (e.g., Tailwind)
Carbohydrate Profile	Often includes complex carbs, fiber, and varied sugars.	Primarily simple sugars for fast absorption.	Simple sugars blended for quick absorption and electrolyte delivery.
Digestibility	Can be harder to chew and digest at high intensity.	Typically very easy to digest, designed for runners.	Easiest to absorb; ideal for sensitive stomachs.
Taste & Texture	Highly varied, offering flavor relief from sweets.	Often intensely sweet, can cause palate fatigue.	Flavor options vary, but lack textural variety.
Portability	Can be bulky and messy; requires preparation.	Highly compact, clean, and easy to carry.	Requires bottles or a hydration pack.
Nutrient Balance	Can naturally include sodium, protein, and fat.	Primarily carbohydrates; may include caffeine.	Specifically formulated with carbohydrates and electrolytes.

The Critical Role of Hydration and Electrolytes

Adequate hydration is non-negotiable for ultra running. Aim to drink 400-700 ml of fluid per hour, potentially more in hot or humid conditions. However, simply drinking water isn't enough. As you sweat, you lose electrolytes, particularly sodium, which are vital for nerve and muscle function. Replenishing these is key to preventing cramping, nausea, and a dangerous condition called hyponatremia (low blood sodium). Use electrolyte drinks or take salt capsules in addition to water. A personalized sweat rate test during training can help you determine your individual fluid and sodium needs.

Using Aid Stations Strategically

Aid stations are a wonderful part of the ultra experience, offering a variety of food and drinks. However, they should not be your entire plan. Check the race website beforehand to know what they will be offering. You should carry your own tested backup fuel, especially for unique needs or in case the aid station offerings don't sit well with you. Use aid stations to supplement your supply, grab a familiar favorite, or top off your water bottles.

Conclusion: Perfect Your Personal Ultra Plan

There is no one-size-fits-all fueling strategy for a 50K ultra. Success is a product of consistent training and careful, personalized nutrition planning. Test all your fuel and hydration options during your long training runs to know exactly what works for you. Start eating and drinking early, stick to a regular schedule, and embrace variety. By training your gut as rigorously as your legs, you'll cross the finish line energized and ready for recovery. For more specific guidance on creating a fueling plan, Hammer Nutrition offers excellent resources and sample plans, such as their How to Fuel Guide: 50k Trail Run.

Your Pre-Race and Post-Race Nutrition Plan

Your race-day fueling starts well before the first step. For 2-3 days prior, increase your carbohydrate intake with easy-to-digest sources like pasta, rice, and potatoes, while reducing high-fiber foods to minimize gut issues. The morning of the race, have a light, familiar carb-rich breakfast 2-3 hours before the start. After finishing, consume a meal with a 3:1 or 4:1 carb-to-protein ratio within 30-60 minutes to kickstart recovery. Continue to hydrate and eat balanced meals over the next day or two to replenish fully.

Frequently Asked Questions

How many calories should I consume per hour during a 50K ultra?

Most runners should aim for 200-250 calories per hour, primarily from carbohydrates. This is the amount most stomachs can process effectively during sustained exercise.

Is it okay to only use energy gels for a 50K?

While possible, relying solely on gels can lead to 'flavor fatigue' and upset your stomach. Most experienced ultra runners supplement with real food and electrolyte drinks for variety and balanced nutrition.

What are good examples of 'real food' for a 50K ultra?

Good options include salted boiled potatoes, bananas, rice balls, PB&J sandwiches, salted pretzels, and rice cakes. These offer varied tastes and textures.

How important are electrolytes during an ultra?

Extremely important. Electrolytes, especially sodium, are lost through sweat and are essential for muscle and nerve function. Replacing them with electrolyte drinks or capsules prevents cramping and hyponatremia.

Should I change my diet in the days leading up to the race?

Yes. In the 2-3 days before the race, increase your intake of easy-to-digest carbohydrates like rice and pasta, while reducing high-fiber foods to minimize the risk of GI distress on race day.

When should I eat after finishing a 50K?

The ideal recovery window is 30-60 minutes after the race. Aim for a 3:1 or 4:1 carbohydrate-to-protein ratio to help replenish glycogen stores and repair muscles.

What is the 'golden rule' of ultra nutrition?

The golden rule is 'Nothing New on Race Day'. Only consume foods and drinks during the race that you have already practiced with during your long training runs to avoid unexpected stomach issues.