When you hear about 90–100 g of carbohydrates per hour, it can seem unrealistic if you already experience stomach issues from a single gel on your run. But just like your legs can be trained to run farther and cycle faster, you can often also train your stomach and digestion to handle more energy along the way.
Here you’ll get a practical guide on how, step by step, you can work on adapting your stomach to a higher carbohydrate intake, so you perform better on long sessions and on race day, while also reducing the risk of stomach issues such as cramps, nausea, or the need for unplanned stops.
Why your stomach reacts when you increase carbohydrates
Stomach issues during running, cycling, and triathlon can often be related to one or more of these factors:
- Too much carbohydrate per hour compared to what your gut is used to
- Overly concentrated drinks with too much sugar and too little fluid
- Large intakes once per hour instead of small, frequent intakes
- High intensity and heat, which in themselves can make the stomach more sensitive
The body can’t absorb unlimited amounts of carbohydrate per hour. If you exceed your personal tolerance, some of the carbohydrates can remain in the gut, where they can bind fluid and contribute to bloating, gurgling, nausea, or diarrhea.
A more even rhythm, for example smaller amounts every 10–15 minutes, is experienced by many as gentler on the stomach than taking a large gel once per hour. It can also contribute to a more stable energy supply during training and racing.
What it means to train your gut
When you train your gut, you accustom your intestines and digestive system to specific amounts and types of carbohydrates under load. In practice, it typically means making the following a fixed part of your training:
- More frequent carbohydrate intake during longer sessions
- Larger amounts per hour than you may be used to
- Specific types of products such as gels, chews, and energy powder, so you learn what works for you
Research and practical experience suggest that the gut’s carbohydrate transporters can adapt to repeated strain. Over time, you can therefore often:
- Handle a higher number of grams of carbohydrates per hour
- Experience fewer stomach issues at the same intake
- Utilize energy intake better, especially on sessions longer than one and a half to two hours
It often makes the most sense to focus on gut training in periods when you’re already doing long and/or hard sessions. This could be long Sunday rides, marathon build-ups, tri blocks, or runs over two hours. Here, you can make your fueling plan a fixed part of training on par with intervals and strength sessions.
Step by step from 30 to 90 grams of carbohydrates per hour
How high you can get is individual. But many recreational and ambitious endurance athletes can, with a systematic approach, often move from around 30–40 g of carbohydrates per hour up toward 60–90 g per hour, depending on intensity, duration, and individual factors.
One possible progression could look like this:
- Find your current level by starting at an amount you know you can handle, for example 30–40 g per hour on your long sessions
- Plan three to six weeks of gut training and pick one to two long sessions per week that you use as test sessions
- Increase gradually by adding about 10–15 g of carbohydrates per hour per week, for example 40 g in week one, 50–55 g in week two, 60–65 g in week three, 70–75 g in week four, and 80–90 g in week five, if it fits your sport and your level
- Back off if you get stomach issues, and return to the last level you could handle, staying there for one to two weeks while potentially adjusting the distribution between fluids, fructose, and number of gels
- Match intensity and race setup so you test your plan at a duration and intensity similar to what you expect in competition
Gut training at a very easy pace is not always enough if you need to hold race pace on the day. Therefore, it can be a good idea to test your strategy on selected key sessions.
If you’re unsure where you should land, you can get extra inspiration from the article about how many carbohydrates per hour on the bike, where you’ll find concrete numbers and examples for 60–90 g per hour in practice: how many carbohydrates per hour on the bike.
Choosing gels, chews, and sports drink for your stomach
There isn’t one solution that fits everyone. It depends on your stomach, your sport, and your everyday logistics with pockets, bottles, and possible aid stations along the way. You can use the following considerations as a starting point:
Energy gels
- Contain a lot of carbohydrates in a small volume
- Are easy to dose, often 20–25 g per gel
- Typically require extra fluid on the side
PurePower’s range of energy gels for high carbohydrate intake per hour can make it easier to plan, for example one gel every 20–30 minutes, depending on your goal and your overall plan.
Chews as an alternative to gels
- Can be taken in small bites along the way
- Make it easier to get, for example, five to ten grams at a time
- Are often experienced as more palatable over many hours
A practical example is chews as an alternative to gels, where you can take one to two pieces every 10–15 minutes and in that way maintain a steady energy supply.
Sports drink and energy powder
- Provide a continuous supply of carbohydrates throughout the hour
- Often combine carbohydrates and electrolytes in the same product
- Assume that you drink the planned amount
With PurePower’s energy powder Carbo Race for bottle fueling, you can, for example, plan 30–60 g of carbohydrates per hour via your bottle, depending on how you mix it.
Many endurance athletes use a combination, for example:
- About 30–40 g per hour from Carbo Race in the bottle
- About 20–40 g per hour from gels or chews
It can be an advantage to train with the same products and flavors you expect to use on race day, so you know how your stomach reacts. Avoid major changes to your setup right before the start.
Fluids, electrolytes, and the strength of your mix
Even a well-thought-out carbohydrate strategy can be affected if fluids and salts don’t keep up. Typical challenges can be:
- Many gels without sufficient water alongside
- Very concentrated sports drink in hot weather
- Only water in the bottle combined with high carbohydrate intake from gels
A couple of basic principles can help you along the way:
- Follow the mixing instructions on, for example, Carbo Race with electrolytes to mix yourself, so you hit a concentration that many stomachs can typically handle better
- Ensure regular fluid intake, often somewhere between 500 and 800 ml per hour depending on temperature and sweat loss
- Use extra electrolytes on hot days or with a high sweat rate to support fluid balance and stomach comfort
If you sweat a lot or train in the heat, consider adding a dedicated electrolyte source like Hydro Tabs Electrolytes to support fluid balance.
Always think of carbohydrates, fluids, and electrolytes as a complete package. Adjust only one thing at a time when you test, so you can more easily assess what works for you and what makes your stomach react.
Examples of a fueling plan per hour
Below you’ll get two simple suggestions for how you can distribute carbohydrates when your stomach is reasonably accustomed to intake under load. Adapt them to your own products and your pace.
Example for running two to three hours, about 70 grams per hour
- Every 15 minutes about 150 ml Carbo Race, which provides around nine to ten grams of carbohydrates
- Every 30 minutes one gel with about 20–25 grams of carbohydrates
That adds up to about 35 grams of carbohydrates from drink and about 35 grams from gels, for a total of about 70 grams per hour.
Example for cycling three to four hours, about 80 grams per hour
- One bottle with 500 ml Carbo Race per hour, which provides about 30–40 grams of carbohydrates
- Every 20–30 minutes one to two chews with about five to ten grams of carbohydrates
- Every 40–45 minutes one gel with about 20–25 grams of carbohydrates
This typically ends up at around 40–45 grams of carbohydrates from drink and about 35–40 grams from gels and chews, totaling about 75–85 grams per hour.
Always adapt the plan to your own products, your intensity, and your experience, and make sure to test it several times in training before using it for competition.
Your gut is part of your training
Your gut is a part of the body that in many cases can be conditioned to intake under load, just like legs, lungs, and mind develop through training. With a gradual build-up, a well-considered combination of sports drink, gels, and chews, and a focus on fluids and electrolytes, you can often improve your tolerance over time.
It requires planning and patience, but many find that it can contribute to a more stable energy supply and fewer stomach worries on the sessions where it really matters.