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How to avoid ‘runner's stomach’: TikTok running myths debunked
Written byLiz Connor
Reviewed byHeeral Patel
Also known as ‘runner’s belly’ or ‘runner’s gut’, this uncomfortable condition can quickly derail your plans for a PB so, we asked sports nutritionists to help us digest the facts
Summary
1Focus on eating low-fat, low-fibre meals
"A large carbe-rich meal at least two to three hours before running is ideal. Some runners skip meals before a run, but this can backfire...”
2Always make sure you’re hydrated
“Dehydration during a run is the last thing you need. Make sure you have plenty of fluid throughout the day to keep you feeling your best...”
3What’s true carb loading?
“This is where over two or three days, you build higher levels of carbs into your diet along with well-balanced meals... “
Can eating too close to a run destroy your target pace? Does coffee help you run faster? Should you bother with gels? When it comes to a runner's nutrition, it can be difficult to sort fact from fiction.
But with a 2017 questionnaire finding that gastrointestinal symptoms could affect up to 90% of runners during endurance races, it’s clear that ‘runner’s stomach’ – aka the diarrhoea, abdominal pain and cramping that can often strike during or after a race – is a common issue on the track.
To help you avoid this trifecta of unpleasant GI issues, we asked sports nutrition coaches to unpack some of the most popular running nutrition myths currently circulating on social media.
Myth 1: You should never eat before a run
Some runners attempt to prevent stomach discomfort by skipping meals altogether before a run, but this can easily backfire, especially during longer or high-intensity runs when the body relies on carbs for energy.
"Fasted running can work for some, but studies show negligible performance advantages," says performance nutritionist and registered dietitian Ian Perkins. "If you’re running at higher intensities than Zone 2 (which is low-intensity workout), where carbohydrates begin to be utilised [over burning fat], then it becomes essential to have some form of carbs ready in the body."
The fix: Instead of running on an empty tank, focus on eating low-fat, low-fibre, moderate-protein meals well before your run.
"A large carbohydrate-rich meal at least two to three hours before running is ideal," suggests Ian. “Try a breakfast of Weetabix with semi-skimmed milk, honey and a small glass of orange juice to provide enough energy without overwhelming your digestive system.”
Myth 2: Drinking water right before running causes stomach cramps
Many runners believe that gulping large quantities of H2O just before a run will lead to painful stomach cramps. In fact, it may be the opposite: a study1 suggests that dehydration can aggravate gastrointestinal complaints during exercise.
"While chugging lots of water right before a run can definitely cause some mild stomach discomfort, drinking water shouldn’t be avoided, as it’s an important step to warding off race-day dehydration," warns registered dietician nutritionist Kristy Baumann.
The fix: "Instead of drinking water at the starting line, steadily sip on fluids throughout the day to stay hydrated and can help prevent stomach issues during your run," advises Kristy.
Of course, not all stomach issues can be fixed water, so if it’s long-lasting make sure to speak to a healthcare professional,
Myth 3: You should eat a big dinner the night before a race
Many runners pile their plates high with pasta the night before a big run, thinking they’re stocking up on all-important energy. But the next morning, they might wake up feeling bloated, sluggish and anything but race-ready. “This is because the body has a limited capacity for storing glycogen2 and cramming in excessive carbs in one sitting won’t maximise those reserves,” says physiotherapist Kieran Sheridan.
“True carb-loading is not about having one gigantic meal,” he adds. “It’s practiced over two or three days, where you build progressively higher levels of carbs into your diet while making sure that your meals are well-balanced. Overloading in one sitting can end up doing more damage than good, causing gastrointestinal upset, sleep deprivation and the feeling of heavy limbs3 on competition day.”
The fix: “Start increasing your carb intake two to three days before your race, focusing on easily digestible options like rice, oats and potatoes,” says Kieran.
Myth 4: You only need to hydrate on hot days
Many runners assume that hydration is only a thing to consider if their race falls on a heatwave, but stomach issues brought on by dehydration can happen year-round, even in the cooler months.
"Urine colour is probably your best indicator of hydration – a pale yellow generally means you’re well hydrated, while darker urine suggests dehydration,"4 notes Ian. "Runners should aim for at least three litres of fluids daily,5 as fluid losses increase during runs, even in cold weather."
The fix: "Try adding an electrolyte tablet to at least 750ml of water before running to help support hydration,” says Ian. “Sipping a sports drink in the hour leading up to your race can also provide extra carbohydrates and reduce the need for a large pre-run meal.”
Myth 5: Food is the only thing that can give you cramps
It’s easy to blame a torturous mid-race stitch on your choice of breakfast, but it’s not the only culprit. In fact, your breathing technique can have just as much of an impact.
A scientific review published in 20236 found that fast, shallow breathing can cause the body to increase carbon dioxide, which can lead to alkalosis, a state linked to muscle cramps and spasms related to the nervous system. A further small study7 involving 23 people with gastroesophageal reflux disease (GERD) found that those who practiced diaphragmatic (deep) breathing were more likely to experience fewer acid reflux episodes and less digestive discomfort than those who didn’t.
The fix: Focus on slowing your breath right down to avoid cramping. “Taking deep, controlled breaths through your nose and out your mouth will stop you from gulping air as you run," says Kristy.
Myth 6: If you have a sensitive stomach, running isn’t for you
Having a sensitive stomach doesn’t mean you can’t nab a marathon medal – it just means your digestive system, like any other muscle group in the body, needs focused attention.
"Just like you need to train your cardiovascular, neuromuscular and musculoskeletal systems, you also need to train your digestive system," says Ian. "The longer you run, the more blood is pumped away from the stomach, which can cause GI sensitivity during endurance efforts."
The fix: "Introduce easily digestible foods at least 30 minutes before a run, and build up tolerance with short, frequent training runs," says Ian.
By gradually training your gut over the weeks leading up to an event, you can help your digestive system adapt to the demands of endurance efforts, making all the difference to your comfort come race day.
The final say
Dealing with a dodgy tummy is never fun, but as our experts remind us, the key to staying comfortable lies in focusing on fueling with easily digestible foods, staying hydrated and practicing good breathing techniques.
If you experience chronic tummy issues, please speak to your doctor for advice. And if you’re still unsure, we have experts ready to offer personalised guidance and help you understand which gels and running products are right for your training needs.
This article provides informational advice and is not a substitute for medical care. Curated by experts for accuracy, we take great care to ensure the information is up-to-date and relevant. However, you should always consult your GP or healthcare professional before using supplements or alternative products, particularly if you have medical conditions or are under supervision.
1. van Nieuwenhoven MA, Vriens BEPJ, Brummer RJ . M, Brouns F. Effect of dehydration on gastrointestinal function at rest and during exercise in humans. European Journal of Applied Physiology. 2000 Dec 13;83(6):578–84.
2. Murray B, Rosenbloom C. Fundamentals of Glycogen Metabolism for Coaches and Athletes. Nutrition Reviews. 2018 Feb 10;76(4):243–59
3. Mata F, Valenzuela PL, Gimenez J, Tur C, Ferreria D, Domínguez R, et al. Carbohydrate Availability and Physical Performance: Physiological Overview and Practical Recommendations. Nutrients. 2019 May 16;11(5):1084
4. NHS South Tees Hospitals. Urine Colour Chart [Internet]. NHS [cited 2024 May 9]. Available from: https://www.southtees.nhs.uk/wp-content/uploads/2022/08/Urine-colour-chart.pdf
5. Judge LW, Bellar DM, Popp JK, Craig BW, Schoeff MA, Hoover DL, et al. Hydration to Maximize Performance and Recovery: Knowledge, Attitudes, and Behaviors among Collegiate Track and Field Throwers. Journal of Human Kinetics [Internet]. 2021 Jul 10;79(1):111–22. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8336541/
6. Migliaccio GM, Russo L, Maric M, Padulo J. Sports performance and breathing rate: What is the connection? A narrative review on breathing strategies. Sports. 2023 May 1;11(5):103.
7. Halland M, Bharucha AE, Crowell MD, Ravi K, Katzka DA. Effects of Diaphragmatic Breathing on the Pathophysiology and Treatment of Upright Gastroesophageal Reflux: A Randomized Controlled Trial. The American Journal of Gastroenterology [Internet]. 2021 Jan 1;116(1):86–94. Available from: https://pubmed.ncbi.nlm.nih.gov/33009052/
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