Few things can derail marathon day faster than gastrointestinal (GI) distress. Bloating, cramps, nausea or emergency toilet stops can turn months of training into a frustrating battle with your own body. For endurance runners, stomach issues are incredibly common, but they’re not inevitable.

In most cases, GI distress is linked to how, what, and when you fuel. With effective marathon training and a nutrition strategy built on simple, natural ingredients, you can significantly reduce risk and maintain steady energy and focus from start to finish.

During a marathon, blood flow is redirected away from the digestive system and towards working muscles. Digestion slows, while the repetitive impact of running adds further stress to the gut. Combine this with dehydration, race-day nerves, or poorly chosen foods, and digestive discomfort becomes much more likely.

Highly processed products, artificial sweeteners, and overly concentrated sugars can also be difficult to tolerate when your system is under strain. That’s why many runners experience problems even if they feel fine eating the same foods at rest.

One of the most effective ways to avoid GI distress is to train your gut alongside your physical training. Your digestive system adapts through repetition, just like your muscles do.

Long runs are the ideal opportunity to practise race-day nutrition. Using the same products, quantities and timing in training helps your body learn what to expect. By the time race day arrives, your gut recognises the fuel and processes it more efficiently.

This is where natural, whole-food-based energy can make a meaningful difference. Veloforte products are made from whole, plant-based ingredients, designed to deliver energy without overwhelming the digestive system. When used consistently, they become a trusted part of your routine rather than a risk. We have options such as our overnight oats, which are brilliant carb sources that can be easily and slowly digested throughout your training.

Your pre-marathon meal should top up glycogen stores without overloading your digestive system.

Aim for:

• Low fibre

• Low fat

• Moderate protein

• Easily digestible carbohydrates

Great options include white rice, oats, bananas, toast with honey, or Veloforte energy bars you’ve already tested in training. Eating 3–4 hours before the start gives your body time to digest the pre-race fuel fully.

Avoid last-minute experiments, even “healthy” foods like nuts, seeds, or large smoothies, can cause trouble under race stress.

Finally, taking on too much fuel at once is a common cause of nausea and cramping. Instead, steady, regular fueling helps maintain energy levels without overwhelming the stomach.

Most runners aim to consume carbohydrates at regular intervals throughout the race, rather than in large doses. Veloforte’s chews and gels are designed to support this approach, offering naturally balanced energy without artificial ingredients that can irritate the gut when intensity rises.

Listening to your body is critical throughout race day, including hydration. Hydration plays a crucial role in digestion as dehydration can slow gastric emptying, while overhydration can lead to bloating and discomfort.

Drinking to thirst, taking small sips regularly and including electrolytes in longer races helps maintain fluid balance and supports digestion. Avoiding the temptation to gulp large volumes at aid stations can also prevent that heavy, sloshing feeling in your stomach late in the race.

Even with the best planning, it’s important to stay flexible. If your stomach starts to feel unsettled, easing the pace slightly or delaying your next fuel intake can give your gut time to settle.

Pushing through severe discomfort often makes things worse. A small adjustment can be enough to restore balance and keep you moving forward.

Avoiding GI distress in a marathon isn’t about perfection. It’s about simplicity, consistency and choosing fuel your body recognises and trusts.

By training your gut, eating strategically and relying on natural, well-tested running nutrition like Veloforte, you give yourself the best chance to run strong, without unwanted interruptions, all the way to the finish line.