How to Fuel an Ultra — with Guidance from Leading Sports Nutritionists (Using THE LAP as our example ultra)
- High Peak Running
- Mar 14, 2024
- 4 min read
Updated: Oct 22
When you run or walk for many hours in an ultramarathon, your body needs a steady supply of energy — mainly carbohydrate, plus some protein and/or fat — along with fluids and electrolytes. If you don’t get that balance right, you risk “bonking” (running out of energy), developing gut issues, or being forced to slow down significantly.
What is CHO?
In this guide, you’ll see the term CHO, which stands for carbohydrate — the body’s primary source of fast energy. During endurance events, CHO intake is typically measured in grams per hour (g/hr). Managing this intake carefully helps you stay fuelled without upsetting your stomach.
The Science Behind Ultra Fueling
This article draws on the work of several leading sports nutritionists and endurance fueling experts, including:
Dr. Asker Jeukendrup — Sports scientist, founder of Mysportscience.com, and researcher into carbohydrate metabolism and endurance fueling.
Paul Booth — UK-based sports nutritionist specializing in endurance performance and practical fueling for ultra-distance athletes.
Renee McGregor — Registered Sports & Eating Disorder Dietitian, author of Training Food and The Female Athlete, focusing on sustainable fueling strategies.
Nigel Mitchell — Performance nutritionist for Team Sky and British Cycling, known for real-food fueling approaches.
International Society of Sports Nutrition (ISSN) — Authors of key position stands on endurance nutrition.
Key Takeaways from the Experts
Train your gut — Regularly practice your race-day fuelling plan in training to increase your gut’s ability to absorb carbohydrates efficiently and comfortably. (Mysportscience.com)
Use multiple carbohydrate sources — Combining glucose and fructose improves absorption and reduces stomach upset.
Fuel consistently — Jeukendrup and Booth recommend 60–90 g CHO/hr, up to 120 g/hr for well-trained athletes.
Add some protein and fat — McGregor and Mitchell highlight that small amounts of protein can reduce muscle damage and that modest fat can help during slower efforts.
Hydrate smartly — Replace 400–800 ml of fluid per hour and 300–600 mg sodium every 60–90 minutes, adjusting for temperature and sweat rate.
Practice everything — Your body’s response to food and drink is personal. Test all products and timings in training before race day.
THE LAP — Example Race Context
THE LAP is a 47-mile / 75 km ultra trail race around Lake Windermere in the Lake District. (thelap.co.uk)
Race Setup
5 fully stocked feed stations
1 halfway / drop bag station at Troutbeck
Food and drink available:
Water
Cordial (flavoured drink)
Electrolyte / energy drink
Coke (non-diet)
Energy bars and gels
Salty snacks
Sodium options
Hot pizza (Troutbeck station – regular and vegan/gluten-free)
Hot meal for finishers
⚠️ Note: If your fuelling depends on specific products or brands, bring your own backup. The aid stations are excellent but may not match your exact needs.
How Much to Eat and Drink
Below are practical example guidelines for a 70 kg athlete. Adjust for your size, pace, and weather conditions.
Example Hour-by-Hour Plan (Steady Runner)
0:00 – Start → Sip electrolyte drink (~25 g CHO)
Every 30–45 min → Eat 20–30 g CHO (gel, chew, bar, or small real food)
At Aid Stations → Refill bottles, take one CHO source (~20–30 g)
Halfway (Troutbeck) → Eat a small meal (pizza slice or savoury snack), refill bottles, and adjust salt/electrolytes
Final 10 miles → Increase small, frequent CHO doses as fatigue builds
Race-Day Tips
Mix sweet and savoury to avoid flavour fatigue (Mitchell).
Eat early — don’t wait for hunger (Jeukendrup).
Plan for weather — heat increases fluid needs.
Watch your gut — if bloating, reduce intake briefly and sip water.
Pack variety — quick carbs, solids, and “comfort” snacks for late race.
Label your drop bag clearly for Troutbeck.
THE LAP Fuel & Hydration Planner
Hydration & Electrolyte Notes
Fluids: 400–800 ml/hour
Electrolytes: 300–600 mg sodium per hour
Monitor: Cramping, bloating, or swelling → adjust intake
Personal Checklist
☐ Practice fuelling in training
☐ Test all brands/flavours
☐ Prepare Troutbeck drop-bag
☐ Carry backup CHO and salt
☐ Mark station stops
Summary
Fuelling an ultramarathon is about strategy, practice, and personal awareness, not guesswork. By following the science from Asker Jeukendrup, Paul Booth, Renee McGregor, and Nigel Mitchell, you can learn to train your gut, manage hydration, and keep your energy steady across every mile of THE LAP — whether you’re racing, jogging, or hiking to the finish.
References
Jeukendrup, A. (Mysportscience). Fueling for Endurance Sports. https://www.mysportscience.com
Booth, P. (2022). Endurance Nutrition Strategies. paulboothnutrition.com
McGregor, R. (2019). Training Food: Get the Fuel You Need to Achieve Your Goals. Bloomsbury Publishing.
Mitchell, N. (2020). The Plant-Based Cyclist: A Nutrition Guide for Performance.
International Society of Sports Nutrition. Position Stand: Nutritional Considerations for Endurance Athletes. PMC6839090
Precision Hydration. Preparing Your Fuelling and Hydration Plan for Ultra Racing. precisionhydration.com
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