What To Eat Before An Endurance Event: A Low-Fibre, Simple-Carb Fuelling Guide

The days before an endurance race are not the time to experiment. The goal in the 1–3 days before the gun goes off is simple: top up glycogen stores, keep the gut calm, and stay well hydrated - without introducing anything that could cause a mid-race bathroom emergency. That means leaning on low-fibre, simple carbohydrates, steering well clear of spicy food, and matching your carb intake to your sex, since men and women don’t respond to carb loading in quite the same way.

Table Of Contents

• Why Low Fibre And No Spice
• Carb Loading: What To Actually Eat
• Foods To Build Meals Around
• Hydration And Electrolytes Matter As Much As Carbs
• Take Home Points

Why Low Fibre And No Spice

During exercise, blood is redirected away from the gut and towards working muscle and the skin (for cooling). Combined with a high-fibre or high-residue meal sitting in the gut, this is a classic recipe for “runner’s gut” - cramping, bloating, and an urgent need to stop mid-race ¹. Surveys of endurance athletes show high-fibre foods, fatty foods, and spicy or heavily seasoned dishes are among those most commonly avoided in the 24 hours before racing because of their link to exercise-induced GI symptoms ². In the final one to three days before race day, swap wholegrain bread for white, salad for cooked and peeled vegetables, and skip the hot sauce, curry paste and chilli altogether.

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Reduced blood flow to the intestines is called splanchnic hypoperfusion ¹.

Carb Loading: What To Actually Eat

Loading up on carbohydrate in the 1–3 days before an endurance event improves performance by helping the body store more fuel than usual - men can typically lift muscle glycogen by up to 40% this way, translating to a 2–3% faster finish time over events longer than 90 minutes ³˒⁴. Guidelines put this at roughly 8–12g of carbohydrate per kilogram of body weight per day for men ⁵˒⁶. Women’s response is more variable - hormonal shifts across the menstrual cycle and oral contraceptive use appear to blunt the effect somewhat - so the usual target is a slightly lower 6–8g/kg/day ³. In practice, that just means making carbs the star of every meal and snack for a few days, not a science project.

Foods To Build Meals Around

• White bread, bagels, English muffins, crumpets, white wraps
• White rice, jasmine or sushi rice, rice noodles, plain (white) pasta or gnocchi
• Potatoes and sweet potato, skin off, mashed or boiled
• Rice cakes, pretzels, plain crackers
• Ripe bananas, melon, grapes, tinned or skinned stone fruit
• Cornflakes, rice bubbles, other low-fibre cereals with milk
• Pancakes, pikelets, waffles with honey, jam or maple syrup
• Juice, carb electrolyte drink mixes, jelly lollies, honey - easy extra carbs when you can’t fit in more food

Meal ideas:

• Breakfast: bagels with honey or jam; pancakes/pikelets with maple syrup and banana; white toast with peanut butter and banana; rice bubbles with milk
• Lunch: sushi rolls with a side of pretzels; white bread sandwich (sliced chicken or turkey, no salad) with a side of chips; rice bowl with teriyaki chicken
• Dinner: plain pasta with a mild tomato or bolognese sauce and lean protein; rice with grilled chicken or fish and a soy-based dressing; risotto
• Snacks: pikelets, banana, low-fibre muesli bar, jelly lollies, a glass of juice or a sports drink

Eating out / takeaway options that still fit the brief:

• Sushi/Japanese → California or cooked-fillings rolls, teriyaki chicken don with extra white rice — skip the spicy mayo, wasabi and kimchi
• Italian → plain pasta with napolitana or bolognese (not arrabbiata), a side of garlic bread, risotto
• Café → a bagel, pancakes, banana bread or a fruit smoothie/juice
• Noodle bar → plain fried rice or noodles with chicken in a mild soy sauce - hold the chilli, laksa paste or curry
• Burgers → Plain chicken, beef or fish burger (light on sauce), fries.
• Bakery → scrolls, buns, croissants, scone or muffins in moderation

Male example — 70–90kg, ~800g carbs/day (roughly 8–12g/kg/day):

• Breakfast: 3 bagels + 4 tbsp maple syrup + 1 banana
• Snack: 6 pikelets + 2 bananas + 400 mL orange juice
• Lunch: 2 sushi rolls + a large handful of pretzels + a can of soft drink
• Snack: 500mL carb electrolyte drink mix + 2 rice cakes with honey
• Dinner: 3 cups of white rice with grilled chicken breast, a soy-based dressing, and a dinner roll
• Snack: 2 scoops of ice cream

Female example — 55–75kg, ~450g carbs/day (roughly 6–8g/kg/day):

• Breakfast: 2 bagels + 3 tbsp maple syrup
• Snack: 4 pikelets + 2 bananas
• Lunch: 1 sushi roll + 2 handfuls of pretzels
• Snack: 400 mL orange juice
• Dinner: 2 cups of rice with sliced avocado, a handful of chicken breast, and 2 tbsp coconut aminos dressing

Both examples sit toward the middle of their respective ranges - a 70kg man at 8g/kg needs ~560g, while a 90kg man at 12g/kg needs ~1080g, so adjust portions up or down for your own weight and the exact end of the range you're targeting. The same applies for the female example across the 55–75kg, 6–8g/kg span.

Hydration And Electrolytes Matter As Much As Carbs

Plain water alone doesn’t fully hydrate the body - sodium is needed alongside water for effective fluid retention and absorption ⁷. Build in foods and drinks that carry both fluid and electrolytes rather than relying on water alone:

• Orange juice or sports drinks (fluid + potassium/sodium)
• Pretzels and salted crackers (sodium)
• Bananas (potassium)
• Coconut water
• An electrolyte tablet or sachet the night before and morning of the race

This lines up with sports-medicine guidance, which recommends pairing sodium with fluid before exercise to keep electrolyte levels stable - everyone sweats differently, so a one-size-fits-all approach doesn't work ⁷.

Take Home Points

• In the 1–3 days before an endurance event or other endurance event, build meals and snacks around simple, low-fibre carbohydrates
• Avoid spicy or heavily seasoned food
• Load carbs at a level suited to your sex and body weight - roughly 8–12g/kg/day for men and 6–8g/kg/day for women
• Pair that with sodium-containing fluids and electrolyte-rich foods rather than water alone
• Save anything new or untested for after race day, not before it

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

References

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2. Parnell JA, Wagner-Jones K, Madden RF, Erdman KA. Dietary restrictions in endurance runners to mitigate exercise-induced gastrointestinal symptoms. J Int Soc Sports Nutr. 2020;17(1):32.

3. Sims ST, Kerksick CM, Smith-Ryan AE, Janse de Jonge XAK, Hirsch KR, Arent SM, et al. International society of sports nutrition position stand: nutritional concerns of the female athlete. J Int Soc Sports Nutr. 2023;20(1):2204066.

4. Hawley JA, Schabort EJ, Noakes TD, Dennis SC. Carbohydrate-loading and exercise performance. An update. Sports Med. 1997;24(2):73-81.

5. Burke LM, Hawley JA, Wong SHS, Jeukendrup AE. Carbohydrates for training and competition. J Sports Sci. 2011;29(Suppl 1):S17-27.

6. Murray B, Rosenbloom C. Fundamentals of glycogen metabolism for coaches and athletes. Nutr Rev. 2018;76(4):243-59.

7. Sawka MN, Burke LM, Eichner ER, Maughan RJ, Montain SJ, Stachenfeld NS. American College of Sports Medicine position stand. Exercise and fluid replacement. Med Sci Sports Exerc. 2007;39(2):377-90.

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.