Marathon Fuelling Guide: How to Eat for Peak Performance

Preparing for a marathon? Proper race week nutrition can make a big difference in performance, energy and comfort on race day. From carb loading to pre-race breakfast, low-fibre meal swaps, and hydration strategies, knowing what and when to eat ensures your body is fuelled and ready to go. This guide breaks down practical tips for every runner looking to tackle their next marathon with confidence.

Table of Contents

• How Do I Carb Load for a Marathon Without Stomach Issues?

• Which Low-Fibre Foods Are Best Before Race Day?

• How Should I Hydrate in the Days Leading Up to a Marathon?

• What Are Easy Race Night Dinner Ideas for Marathon Runners?

• What’s the Best Pre-Race Breakfast to Boost Performance?

• Quick Recap: Fuelling for Race Day

How Do I Carb Load for a Marathon Without Stomach Issues?

Start increasing carbohydrate intake about 1-3 days before race day. Aim for roughly 5-12g of carbohydrate per kilogram of body weight per day¹,²,⁴⁻⁸. Focus on easily digestible carbohydrate sources such as rice, pasta, potatoes, quinoa, bread, yoghurt, fruit, juice, and even ice cream²,⁷. Spread intake throughout the day and avoid very large portions to minimise gastrointestinal discomfort.

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Carb loading works by maximising glycogen storage in muscles and liver, the key fuel for sustained aerobic exercise. Males may benefit from the higher end (8-12g/kg), while females often tolerate slightly lower amounts (5-8g/kg)²,⁷,⁹.

For more information check out our article on How to Carb Load for a Marathon.

Which Low-Fibre Foods Are Best Before Race Day?

Before race day, choosing low-fibre foods can help prevent bloating, gas, or sudden toilet stops. Good options include white bread, plain bagels, rice, pasta, bakery items, bananas, rice cakes, pancakes, low-fibre cereals, peeled potatoes, dairy products, lean meat, eggs, and tofu. You don’t need to overhaul your meals, simply swap high-fibre ingredients for these low-fibre alternatives while keeping your usual foods and routines.

More low fibre meal options found here → Best food & meals for carb loading: nutritionist's guide

How Should I Hydrate in the Days Leading Up to a Marathon?

In the days leading up to a marathon, start hydrating early by drinking consistently throughout the week. A simple way to monitor hydration is by checking that your urine is light in colour. Include electrolytes 1-2 days before the race, especially in hot or humid conditions. On race morning, aim for 300-500 ml of water with electrolytes 1-2 hours before the start, and sip as needed until the gun.

More everyday hydration tips found here → Everyday Hydration for Endurance Athletes

What Are Easy Race Night Dinner Ideas for Marathon Runners?

For race night dinner, aim for a meal that is high in carbohydrates, moderate in protein, low in fat, low in fibre, and not spicy. Good options include;

• Pasta with a small amount of chicken and tomato sauce

• Rice or quinoa with baked fish and lightly cooked vegetables

• Simple risotto or mashed potatoes with lean protein, or a 

• Vegetarian pizza.

Stick to familiar foods and avoid trying new recipes to minimise the risk of digestive issues on race day.

What’s the Best Pre-Race Breakfast to Boost Performance?

There’s no single “best” pre-race breakfast, as what works is individual, but some options are generally easier to digest and provide effective fuel. Aim to eat 2-3 hours before the start. Simple choices include;

→ 2-3 slices of toast or 1 bagel with a bit of nut butter and banana
→ Rice cakes/pikelets with cottage cheese and jam/honey
→ 2-3 hot cross buns with butter and maple syrup

Tip → Keep caffeine and fat consistent with what your body normally tolerates.

 

Quick Recap: Fuelling for Race Day

No matter what marathon you’re running, race week nutrition is about more than just carb loading. Focusing on low-fibre, easily digestible meals, consistent hydration, and a pre-race breakfast that suits your body can help you avoid GI issues and maximise performance. Stick to familiar foods, spread your carbs over the days leading up to the race, and tailor your hydration to conditions. These small strategies can have a big impact on race day success.

Ash Miller
Dietitian and Nutritionist (Masters)
Bachelor of Physical and Health Education
Instagram: @ashthomo_nutrition

 

References

1. Bosch AN. Carbohydrate loading. In: Mooren FC, Westerterp KR, editors. Encyclopedia of Exercise Medicine in Health and Disease. Berlin: Springer; 2012. p. 144-146.

2. Patterson A. Carb Loading for Success: What You Need to Know [Internet]. Melbourne: Sports Dietitians Australia; 2017 Jun 27 [cited 2025 Nov 11]. Available from: https://www.sportsdietitians.com.au/sda-blog/carb-loading-success/#:~:text=How%20much%20carbohydrate%20do%20I,day%20for%20a%2060kg%20athlete

3. Hargreaves M, Spriet LL. Muscle glycogen stores and fatigue. J Physiol. 2013;591(18):4405‑4413.

4. Kerksick, C. M., Arent, S., Schoenfeld, B. J., Stout, J. R., Campbell, B., Wilborn, C. D., … Antonio, J. (2017). International society of sports nutrition position stand: nutrient timing. Journal of the International Society of Sports Nutrition, 14(1). https://doi.org/10.1186/s12970-017-0189-4

5. Tarnopolsky MA, Zawada C, Richmond LB, Carter S, Shearer J, Graham T, Phillips SM. Gender differences in carbohydrate loading are related to energy intake. J Appl Physiol (1985). 2001 Jul;91(1):225-30. doi: 10.1152/jappl.2001.91.1.225. PMID: 11408434. 7615443.10.1249/MSS.0000000000002850. Epub 2021 Dec 30. PMID: 34974499.

6. Wismann J, Willoughby D. Gender differences in carbohydrate metabolism and carbohydrate loading. J Int Soc Sports Nutr. 2006 Jun 5;3(1):28-34. doi: 10.1186/1550-2783-3-1-28. PMID: 18500960; PMCID: PMC2129154.

7. Sims ST, Kerksick CM, Smith-Ryan AE, Janse de Jonge XAK, Hirsch KR, Arent SM, Hewlings SJ, Kleiner SM, Bustillo E, Tartar JL, Starratt VG, Kreider RB, Greenwalt C, Rentería LI, Ormsbee MJ, VanDusseldorp TA, Campbell BI, Kalman DS, Antonio J. International society of sports nutrition position stand: nutritional concerns of the female athlete. J Int Soc Sports Nutr. 2023 Dec;20(1):2204066. doi:  10.1080/15502783.2023.2204066. PMID: 37221858; PMCID: PMC10210857.

8. Australian Institute of Sport. Carbohydrate Loading Factsheet [Internet]. Canberra: AIS; 2020 [cited 2025 Nov 11]. Available from: https://www.ausport.gov.au/__data/assets/pdf_file/0007/123456/Carbohydrate_Loading_Factsheet.pdf

 

Disclaimer:

The content in this blog is for general information only and is not a substitute for professional medical advice, diagnosis, or treatment. Always speak with your doctor or allied health team before changing your diet, exercise, or taking supplements, especially if you have a health condition or take medication. Please use this information as a guide only. Aid Station doesn't take responsibility for individual outcomes.