What to Eat Before a Long Race: The Low FODMAP Strategy

June 19, 2026

By Kyla Channell, MS, Sports Nutritionist, Nutritional Revolution Founder

What to Eat Before a Long Race: The Low FODMAP Strategy from Lis et al. 2018

Eating low FODMAP for 24 to 48 hours before a long race reduces exercise-associated GI symptom severity by approximately 50% (Lis et al. 2018). The 2025 SDA/USSF position paper (Costa et al.) graded this Grade I evidence — the strongest tier they assign. Race week is not the time for “clean.” It is the time for predictable. Here is the race-week food list and a 48-hour pre-race meal plan.

If you ate oatmeal with chia and berries the morning of your last race and your gut staged a coup at hour three, this article is for you.

The pre-race breakfast trends flooding Instagram — overnight oats, smoothie bowls, Greek yogurt parfaits, sprouted grain toast — share one problem. They are loaded with FODMAPs and fiber. Under the splanchnic ischemia of hard racing, those fermentable carbohydrates become bloating, urgency, cramps, and DNFs.

Lis et al. 2018, published in *Medicine and Science in Sports and Exercise*, ran the controlled study that quantified the fix. Eating a low FODMAP diet for 24 to 48 hours before exercise reduced exercise-associated GI symptom severity by roughly 50%. Costa et al. 2025 — the SDA/USSF Joint Position Statement on exercise-induced gastrointestinal syndrome (EIGS) — graded this Grade I evidence, the strongest tier they assign.

This is one of the most reliably useful nutrition interventions in the entire endurance literature. And it has nothing to do with eating “clean.” It has everything to do with eating predictable.

What are FODMAPs?

FODMAPs are Fermentable Oligo-, Di-, Mono-saccharides And Polyols— short-chain carbohydrates that resist absorption in the small intestine and ferment in the large intestine.

Common high-FODMAP sources hiding in athletes’ kitchens:

Wheat (fructans)
Onions and garlic (fructans)
Apples, pears, mangos, watermelon (excess fructose)
Honey, agave (excess fructose)
Milk, regular yogurt, soft cheeses (lactose)
Cashews, pistachios (galacto-oligosaccharides)
Beans, lentils, chickpeas (galacto-oligosaccharides)
Sugar alcohols in “sugar-free” gels and gum — sorbitol, mannitol, xylitol (polyols)

Outside of race week, these foods are healthy. They feed gut bacteria and support digestion.

Inside race week, they are a liability.

What Lis et al. 2018 actually tested

In a controlled crossover trial, endurance runners ate either a low FODMAP or a high FODMAP diet for 24 hours before a hard exercise session. The low FODMAP arm reported significantly less bloating, urgency, and pain during exercise. Symptom severity dropped by roughly 50%. Performance was not impaired by the dietary swap.

Costa et al. 2025 confirmed and extended this finding through systematic graded review. Of every dietary intervention tested in the EIGS literature, low FODMAP for 24–48 hours pre-race remains one of only three to earn Grade I evidence — alongside carbohydrate during exercise and two-week gut training.

Why FODMAPs ferment when you race

Three things happen during long, hot, hard exercise:

Splanchnic ischemia. Blood gets diverted from your gut to working muscles and skin (for cooling)
Slowed gastric motility. Gut transit slows under exercise stress.
Compromised barrier function. Tight junctions in the intestinal lining open slightly under heat and exertion.

Now add fermentable carbohydrates to that ischemic, slow-moving, leaky gut. The fermentation produces gas. Gas distends the gut. Distension hurts. Distension also drives the urgent need to find a porta-potty that doesn’t exist.

You don’t have IBS. You have a gut running an obstacle course.

Race week food list

This is the list I send my athletes the week before A-races. It is deliberately boring. It pairs cleanly with the carb load (8–12 g/kg/day for 1–2 days pre-race), which is the other half of race-week nutrition.

Eat these (low FODMAP, race-week safe)

Grains: White rice, real sourdough bread (fermented 24+ hours), white pasta, rice noodles, white bagels, cream of rice. Small servings of oats (½ cup max) are usually tolerated.
Proteins: Eggs, plain chicken, white fish, lean beef, salmon. Keep portions moderate; protein slows gastric emptying.
Fruits: Ripe (not overripe) banana, strawberries, blueberries in small servings, oranges, kiwi. Avoid dried fruit.
Vegetables: Carrots, cucumber, lettuce, spinach, zucchini in small portions, white potato, sweet potato in small portions.
Dairy: Lactose-free milk, hard cheeses (cheddar, parmesan), butter.
Snacks: Rice cakes, pretzels, plain crackers, peanut butter (small portions).
Sports nutrition: Most gels, drink mix, chews, and bars made for racing are formulated low-FODMAP. Watch labels for sorbitol, polyols, and excess fructose.

Skip these (high FODMAP, race-week risk)

Wheat-based bread (non-sourdough), bagels, regular pasta in large portions
Apples, pears, mangos, watermelon, dried fruit
Onions, garlic, asparagus, brussels sprouts, cauliflower, mushrooms
Beans, lentils, chickpeas, hummus
Regular milk, most yogurts, soft cheeses, ice cream
Honey, agave, high-fructose corn syrup, “sugar-free” anything
Cashews, pistachios

Want race-week meal targets paired to body weight + day-by-day carb-loading numbers?

Download my free Carb Loading Guide](https://mailchi.mp/nutritional-revolution/free-carb-loading-guide). It pairs the food list above with 8–12 g/kg daily carb targets, two complete loading protocols (3-day and 1-day), and the eating frequency I send to my pros.

A 48-hour pre-race example (75 kg athlete, race Saturday morning)

Thursday breakfast: Cream of rice + honey + ripe banana + black coffee (~95g carbs)
Thursday lunch: Grilled chicken + 1.5 cups white rice + cucumber + olive oil (~80g carbs)
Thursday snack: 4 rice cakes + 1 tbsp peanut butter + sports drink (~75g carbs)
Thursday dinner: White pasta + tomato marinara + grilled chicken + parmesan + sourdough roll (~110g carbs)
Thursday evening snack: Sourdough toast + butter + jam (~60g carbs)

Day total: ~420g carbs (~5.6 g/kg). Friday scales up to 8–10 g/kg.

Race morning is small white rice + ripe banana + black coffee, 2.5 to 3 hours before start.

This sketch is not a prescription. Real plans get individualized to body weight, race duration, training load, and historical gut tolerance.

What this strategy is NOT

Not a permanent low FODMAP diet. That is reserved for clinical IBS, and even then it is used for 4–6 weeks under a dietitian’s care. Chronic low FODMAP impoverishes your gut microbiome.
Not “no fiber forever.” Fiber is fine and beneficial 90% of the year. Race week is the 10% where you strip it down.
Not an excuse to eat junk. White rice, eggs, and chicken are simple. Doritos and Pop-Tarts are not race fuel.
Not a substitute for gut training. Low FODMAP cuts symptom severity. It does not raise your absorption ceiling. Both interventions are needed for big-day execution.

FAQ

Can I eat oatmeal the morning of a race?

A small serving (½ cup or less) is usually tolerable. Large servings with chia, flax, and berries are a common DNF trigger. Test in training first — never on race day.

Is it the gluten that causes problems?

No. The fructans (a FODMAP) in wheat are the issue, not the gluten itself. That is why athletes feel “better off gluten” — they are usually responding to fructans. Sourdough’s long fermentation breaks down most fructans, which is why real sourdough is generally tolerated.

How early before the race should I switch to low FODMAP?

24 hours is the minimum studied (Lis et al. 2018). 48 hours is more conservative and what I use with my pros.

What about coffee?

Plain black coffee is low FODMAP. Skip the oat milk creamer (high FODMAP) and high-lactose dairy. A splash of lactose-free milk or a small amount of hard cream is fine.

Do I need to test FODMAPs in training?

Yes. Individual responses vary. Practice your race-week food list at least twice during your build phase, including a hard simulation workout to confirm tolerance.

Should I avoid FODMAPs the rest of the year?

No. Low FODMAP is a race-week tool, not a lifestyle. Outside of race week, fiber-rich and FODMAP-containing foods are part of a healthy athletic diet.

What about race-morning gels — are those FODMAP issues?

Most performance gels are formulated low-FODMAP. Risk-flag products list sorbitol, mannitol, xylitol, or large amounts of excess fructose. Read the label.

The bottom line

Race week is not the week to be “clean.” It is the week to be predictable. Strip out fermentable carbohydrates, eat boring, and let your training do the heavy lifting.

Costa et al. 2025 graded the science Grade I. Lis et al. 2018 quantified the effect at roughly 50% fewer GI symptoms. The food list is short and the protocol is two days long. The smoothie bowl can wait until Sunday.

Ready to lock in the full race-week plan with carb loading numbers, day-by-day meal timing, and the morning-of fueling timeline I use with my pros? Download my free Carbs for Racing Guide: (https://mailchi.mp/nutritional-revolution/carbs-for-racing.

It pairs with this low FODMAP framework and covers hourly targets, product combinations, and the GI-smart strategy when conditions go sideways.

### Sources

– Lis DM et al. (2018). Low FODMAP diet reduces exercise-associated gastrointestinal symptoms in endurance athletes. *Medicine and Science in Sports and Exercise* 50(1):116–123.

– Costa RJS et al. (2025). SDA/USSF Joint Position Statement on Exercise-Induced Gastrointestinal Syndrome. *Sports Medicine* 55:1097–1134.

– Costa RJS et al. (2017). Systematic review: exercise-induced gastrointestinal syndrome — implications for health and intestinal disease. *Alimentary Pharmacology and Therapeutics* 46:246–265. [doi.org/10.1111/apt.14157](https://doi.org/10.1111/apt.14157)

– Bussau VA et al. (2002). Carbohydrate loading in human muscle: an improved 1 day protocol. *European Journal of Applied Physiology* 87(3):290–295. [doi.org/10.1007/s00421-002-0621-5](https://doi.org/10.1007/s00421-002-0621-5)

– Burke LM, Jeukendrup AE, Jones AM, Mooses M (2019). Contemporary nutrition strategies to optimize performance in distance runners and race walkers. *International Journal of Sport Nutrition and Exercise Metabolism* 29(2):117–129. [doi.org/10.1123/ijsnem.2019-0004](https://doi.org/10.1123/ijsnem.2019-0004)

– Thomas DT, Erdman KA, Burke LM (2016). Position of the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and Athletic Performance. *Journal of the Academy of Nutrition and Dietetics* 116(3):501–528.