How to Train Your Gut for Race-Day Fueling

If you've ever felt sick, bloated or crampy after taking a gel mid-race, the gel itself may not be the whole problem.

Often, the issue is how much carbohydrate you're taking in, how quickly you're taking it, and whether your gut has been trained to handle that intake during exercise.

For long endurance events, common fueling targets can reach 60-90g of carbohydrate per hour, with some highly trained athletes experimenting with even higher intakes. But your gut doesn't automatically tolerate large amounts of fuel just because your muscles need it.

That tolerance has to be practiced.

What gut training actually is

Gut training is the practice of regularly consuming your planned carbohydrate intake during exercise so your digestive system becomes more accustomed to processing fuel while you're moving.

Over time, this can improve carbohydrate tolerance and may also improve how effectively your body absorbs and uses carbohydrate during exercise.

The important point is that athletes vary significantly.

Some people can tolerate relatively high carbohydrate intakes with very little practice. Others experience nausea, bloating, cramping or the urgent need for a toilet when they suddenly increase their intake.

That is why jumping straight into a high-carb race strategy without testing it first is a bad idea.

Your fueling strategy should be trained just like your pacing, equipment and race intensity.

A simple way to build up

Start from an amount of carbohydrate you already tolerate comfortably, then progressively increase it toward your intended race-day target.

You do not necessarily need to begin at 30g per hour if you already tolerate more.

As an example, someone currently comfortable around 30g per hour could progress like this over roughly 4-6 weeks:

The exact progression matters less than the principle:

increase gradually and monitor how your gut responds.

If you experience significant GI problems, don't force the next step just because the plan says you should. Stay at the current intake until it becomes comfortable, then progress again.

Train your gut under realistic conditions

Not every gut-training session needs to be performed at race intensity.

Long, easier endurance sessions are useful for practicing higher carbohydrate intakes because they give you time to work on timing, fluid intake and product choice.

But as race day approaches, some key sessions should become more specific.

That means practicing:

• the same carbohydrate target

• the same products

• similar fluid intake

• similar caffeine intake

• similar timing

• and, where practical, similar race intensity

GI tolerance often changes as exercise intensity increases, particularly during running and harder efforts.

A fueling strategy that feels perfect during an easy ride may not feel the same during a hard race.

Fueling in UAE heat

Heat adds another variable. Higher sweat losses and dehydration can make your gut less tolerant of concentrated carbohydrate, so a plan that works on a cool early-morning ride may not hold up in a hot midday session in Dubai or Abu Dhabi.

If you're training in the UAE:

• Practice in race-like heat. Do some of your key gut-training sessions at the temperature you'll race in, not only in cooler conditions.

• Take your fluids seriously. Concentrated gels need water, and the hotter it is, the more that matters.

• Think about sodium. Heavy sweaters can lose a lot of sodium. Electrolyte tablets or a gel with sodium already built in, such as Applied Nutrition's Elite Energy Gel, can help.

• Progress more cautiously in the heat. If you're moving from cooler months or indoor training, give yourself extra time before raising your carbohydrate intake in hot conditions.

Why glucose and fructose help at higher intakes

At higher carbohydrate intakes, the type of carbohydrate you use starts to matter.

Glucose-based carbohydrates such as glucose and maltodextrin are absorbed through one primary intestinal transport pathway.

Fructose uses a different pathway.

By combining the two, the intestine can use more than one transport mechanism at the same time. This can allow higher rates of carbohydrate delivery and oxidation than relying on glucose-based carbohydrate alone.

That is why many modern endurance products use combinations of glucose or maltodextrin with fructose.

Different products use different ratios.

For example, Enervit's C2:1PRO range uses a 2:1 maltodextrin-to-fructose ratio, while other high-carbohydrate systems use ratios closer to 1:0.8.

The important point isn't that one ratio is automatically best for everyone.

It's that combining multiple transportable carbohydrates becomes increasingly useful as your carbohydrate target rises.

Common gut-training mistakes

• Trying new nutrition on race day. If you haven't practiced with a product in training, race day is not the time to find out how your stomach reacts to it.

• Going straight to the full target. Jumping from very little carbohydrate to 80 or 90g per hour in one session is an easy way to create GI distress.

• Only practicing on easy sessions. Long easy sessions are useful, but your key race-fueling practice should eventually include some race-specific intensity.

• Ignoring fluid intake. Many concentrated gels are intended to be taken with water. Large carbohydrate doses with too little fluid can increase GI discomfort.

• Training the carb number but not the actual products. Hitting 90g per hour in training doesn't guarantee you'll tolerate a completely different combination of gels, drinks, caffeine and flavors on race day.

• Changing too many things at once. If you increase carbohydrate, caffeine and fluid volume all in one session, it becomes difficult to know what caused a problem.

What about gels that don't need water?

Not every gel is the same.

Some products are more concentrated and are best taken alongside water, while others are designed to be consumed without immediately drinking water.

Follow the instructions for the specific product you're using and consider the rest of your fueling strategy.

Your stomach experiences the total combination of:

carbohydrate + fluid + sodium + caffeine + intensity

not each product in isolation.

How much carbohydrate should you aim for?

There is no single number that suits every athlete or every session.

For shorter or easier endurance sessions, you may not need a particularly aggressive fueling strategy.

As duration and intensity increase, carbohydrate requirements generally rise.

A practical framework is:

• Lower intake: suitable for shorter or easier endurance sessions

• Moderate intake: roughly 30-60g per hour for many longer sessions

• Higher intake: roughly 60-90g per hour during long or demanding endurance events

• Very high intake: above 90g per hour is increasingly used by some highly trained athletes, but should be practiced carefully rather than copied blindly

The goal is not to consume the highest number possible.

The goal is to consume enough carbohydrate to support performance while still being able to absorb and tolerate it.

Putting it into practice

Treat your gut like any other trainable system.

Be progressive, consistent and specific.

Build your carbohydrate intake over weeks rather than suddenly changing your nutrition a few days before a race.

As you get closer to competition, practice with the same products and timing you actually intend to use.

If you're targeting 80-90g of carbohydrate per hour, products built around multiple transportable carbohydrates can make those higher targets easier to structure.

Ranges such as Enervit C2:1PRO, SIS Beta Fuel and Maurten can all be used as part of a higher-carbohydrate endurance strategy.

But the brand matters less than whether the total strategy works for you.

If you're not sure which flavors you'll tolerate, the Enervit Carbo Gel C2:1PRO Discovery Pack lets you try several in training before committing to a full box.

Test it in training.

Adjust it when necessary.

And by race day, your nutrition should feel familiar rather than experimental.

Browse our Carbs & Energy Gels collection for gels, chews and drink mixes designed for endurance fueling.

Not sure which brand suits you? Read our guide to the top endurance nutrition brands in the UAE.