Runner’s Gut and Nutrition: Understanding Exercise-Induced Gastrointestinal Syndrome
Content originally provided by Rachel Eagleton, a clinical nutritionist and reviewed and updated by Hannah Pritchard, a registered dietitian and researcher.
Are you suffering from gastrointestinal symptoms associated with exercise? Or have you heard about runner’s gut and want to know more?
If running sends you searching for the nearest toilet, leaves you nauseous halfway through a long run, or causes bloating and stomach cramps; you’re certainly not alone.
Runner’s gut is a common term for the gastrointestinal symptoms that can occur during or after running, particularly during prolonged or strenuous exercise.
This blog explains runner’s gut, exercise-induced gastrointestinal syndrome, and common gastrointestinal symptoms during exercise, plus nutrition strategies that may help you manage them.
But runner’s gut is more than simply having a “sensitive stomach”.
Research at Monash University has helped develop our understanding of exercise-induced gastrointestinal syndrome, where physiological disturbances to gastrointestinal function and integrity that can occur in response to exercise (1).
Quick click contents:
· What to eat before and during running to help manage runner’s gut
· FODMAPs, running and gut symptoms
· Tips for Fuelling if you are prone to runners gut
· Can exercise support gut health?
· When should you get help for runner’s gut?
· Frequently asked questions about runner’s gut
· Summary – Runner’s Gut: Understanding Exercise-Induced Gastrointestinal Syndrome
What causes runners gut?
When exercise becomes prolonged or strenuous, our gastrointestinal system experiences increased physiological stress, which may lead to gastrointestinal symptoms (2).
Multiple factors are involved in this process. For example, blood flow is redistributed away from the gut and more towards working muscles used in exercise. This can affect gastrointestinal integrity and function, contributing to exercise-associated gastrointestinal symptoms (2).
More specifically, researchers at Monash University found that people who exercise for more than 2 hours may be prone to acute or chronic gut issues and as duration and intensity of exercise increased so too did the risk of gut damage, impaired gut function, and both upper- and lower-gastrointestinal symptoms. When the cells of the intestine are injured, the gut becomes more “leaky” allowing toxins to pass into the bloodstream resulting in an initial systemic immune response, the gut transit and digestion of food is reduced, and nutrients already in the gut or that are consumed during exercise may be prone to malabsorption. This scenario of 'exercise-induced gastrointestinal syndrome' may lead to health complications, and exacerbate already established conditions including irritable bowel syndrome (IBS).
For runners, symptoms may include:
· Nausea or vomiting
· Bloating
· Abdominal discomfort or cramping
· Reflux
· Urgency to open the bowels
· Diarrhoea
Your exercise duration, intensity, and environmental conditions can all influence gastrointestinal stress. Individual factors and nutrition choices before and during exercise also matter (2). That’s why managing runner’s gut is rarely as simple as removing one food.
If you’re interested in gastrointestinal health more broadly, read our guide to why gut health matters.
What to eat before and during running to help manage runner's gut
Nutrition can play an important role, but the right strategy is highly individual.
Eating a large meal too close to running, for example, may increase symptoms in some people. The amount and timing of carbohydrate, protein, fat and fibre around exercise can also influence gastrointestinal comfort (2).
However, simply eating less isn’t necessarily the answer. Adequate carbohydrate remains important for prolonged endurance exercise, and emerging research is examining how repeated carbohydrate feeding during training may help athletes better tolerate their fueling strategy (3).
This approach is often referred to as gut training. In practice, it means practising your planned race-day nutrition during training rather than trying unfamiliar gels, drinks or quantities of carbohydrate for the first time on race day.
For further information, this page on carbohydrate loading can give you a few practical ideas.
FODMAPs, running and gut symptoms
Some runners start restricting foods when gastrointestinal symptoms appear. FODMAPs (fermentable carbohydrates) found in a wide variety of foods often receive particular attention.
FODMAPs may be poorly absorbed within the gastrointestinal system, leading to symptoms such as loose stools, wind and bloating (2). However, the low FODMAP diet should only be recommended by a registered dietitian after a comprehensive nutritional assessment.
For selected athletes experiencing runner’s gut, manipulating FODMAP intake around demanding training sessions or competition may be considered as part of an individual nutrition strategy (2). See some examples below.
But, this doesn’t mean every runner with stomach problems requires a low-FODMAP diet or dietary restrictions; it’s important to speak to a healthcare professional first.
Unnecessary restrictions can make meeting energy and nutrient requirements more difficult, so it is worth first establishing what is actually driving your symptoms.
Likewise, commercial tests don’t necessarily provide the answers. See our guides to gut microbiome testing and food intolerance testing before investing in a test.
Tips for fuelling if you are prone to runners gut
Before your run:
A couple of hours before exercise have a high carb, low fibre snack that is easy to digest. Some ideas could include:
- A fruit smoothie using lactose free milk, 1/2 a firm banana and strawberries.
- Low FODMAP cereal (eg gluten free weetbix) with low FODMAP fruit (e.g. blueberries, kiwifruit or a firm banana)
- Low FODMAP toast (e.g sourdough or gluten free variety) with peanut butter and low FODMAP jam like raspberry or strawberry.
During your run:
If you want to use a commercial sports drink or gel you need to watch out for high FODMAP ingredients such as fructose or honey.
After your run:
Once you get home it’s time to refuel with a mixture of carbs to replenish depleted glycogen stores and protein for muscle repair. It’s often easiest just to follow your workout with your next meal. Check out our low fodmap recipe bank for ideas.
Chocolate milk is also a popular option (use cocoa plus sugar plus lactose free milk) or you could make a smoothie.
Can exercise support gut health
It’s important not to come away thinking exercise is bad for your gut. The relationship between gut health and exercise is complex.
Regular physical activity is associated with multiple health benefits, and research is increasingly exploring interactions between exercise, gastrointestinal health and the gut microbiome (4,5).
Problems are more likely to emerge in particular circumstances, such as prolonged or strenuous endurance exercise, rather than movement itself being something to avoid.
A balanced everyday diet still matters. Explore our gut-health-friendly recipes or read about omega-3 foods for mood and brain health for practical ideas.
When should you get help for runner's gut
Occasional mild symptoms may respond to changes in meal timing, hydration or your training nutrition strategy. But frequent runner’s gut, significant diarrhoea, vomiting or pain should be investigated rather than managed by progressively eliminating foods from your diet.
A registered dietitian can review your symptoms alongside your training load, everyday diet, pre-exercise meals, hydration, carbohydrate intake, supplements and race nutrition to develop an individual strategy.
If gastrointestinal symptoms are getting in the way of training or exercise, you can book now for a free discovery call to discuss your needs.
Frequently asked questions about runner's gut
What is runner’s gut?
Runner’s gut is a common term for gastrointestinal symptoms that occur during or after running. Symptoms can include bloating, abdominal cramps, nausea, reflux, urgency and diarrhoea, particularly during prolonged or strenuous exercise (2).
Is runner’s gut the same as having a food intolerance?
No. Gastrointestinal symptoms during exercise don’t necessarily mean you have a food intolerance. Exercise itself may affect gastrointestinal function, while factors such as exercise intensity, duration and what you eat before or during exercise may also contribute (2).
Avoid unnecessarily eliminating foods without first establishing what may be causing your symptoms. You can also read our guide to gluten intolerance symptoms and FODMAPs to learn more about how different foods may contribute to gastrointestinal symptoms.
Can a dietitian help with runner’s gut?
Yes. A dietitian can assess your symptoms alongside your usual diet, training, pre-exercise meals, carbohydrate and fluid intake, supplements and race-day nutrition. This can help identify potential triggers and develop an individual nutrition strategy while ensuring you continue to meet your nutritional requirements (2).
If runner’s gut is affecting your training or exercise, contact Balanced Nutrition Co to discuss how a dietitian may be able to help.
Summary - Runner's Gut: Understanding Exercise-Induced Gastrointestinal Syndrome
Runner’s gut may be influenced by multiple factors, including your exercise intensity, duration, environmental conditions, nutrition, and individual tolerance.
Strategies such as adjusting pre-exercise nutrition, practising race-day fuelling through gut training, and, where appropriate, considering FODMAP intake may help manage symptoms.
It is recommended to speak to a healthcare professional or doctor if you have persistent or significant gastrointestinal symptoms rather than managing them through unnecessary food restrictions.
References
1. Young P, Scheer V, Davidson Z, Biesiekierski JR, Costa RJS, et al. Exploration of exercise-induced gastrointestinal syndrome in endurance-trained adolescents: is there cause for concern in regard to ultra-endurance event participation? Sports Med Open. 2026. Available from: https://link.springer.com/article/10.1186/s40798-026-01061-6
2. Costa RJS, Gaskell SK, Henningsen K, Jeacocke NA, et al. Sports Dietitians Australia and Ultra Sports Science Foundation joint position statement: a practitioner guide to the prevention and management of exercise-associated gastrointestinal perturbations and symptoms. Sports Med. 2025. Available from: https://link.springer.com/article/10.1007/s40279-025-02186-6
3. Martinez IG, Biesiekierski JR, et al. The effect of a repetitive feeding challenge with carbohydrate versus fat on markers of gastrointestinal integrity and systemic outcomes in response to endurance exercise. Int J Sport Nutr Exerc Metab. 2026. Available from: https://journals.humankinetics.com/view/journals/ijsnem/aop/article-10.1123-ijsnem.2026-0043/article-10.1123-ijsnem.2026-0043.xml
4. Al-Beltagi M, Saeed NK, Bediwy AS, El-Sawaf Y, Elbatarny A, Elbeltagi R. Exploring the gut-exercise link: a systematic review of gastrointestinal disorders in physical activity. World J Gastroenterol. 2025;31(22):106835. Available from: https://pubmed.ncbi.nlm.nih.gov/40539198/
5. Hawley JA, Forster SC, Giles EM. Exercise, the gut microbiome and gastrointestinal diseases: therapeutic impact and molecular mechanisms. Gastroenterology. 2025;169(1):48-62. Available from: https://pubmed.ncbi.nlm.nih.gov/39978410/