Decoding Your Fuel: What Gel Do Runners Eat?

October 3, 2025 •

5 min read

For runs lasting over 90 minutes, runners need to consume 30-60 grams of carbohydrates per hour to maintain energy levels and prevent fatigue. Understanding what gel do runners eat is crucial for a successful long-distance performance, as these compact carbohydrate sources provide a vital mid-run boost.

Quick Summary

This guide explores the various types of energy gels available for runners, detailing their ingredients, specific benefits, and correct timing for consumption to fuel long runs and races efficiently.

Key Points

First Gel Timing: For runs over 90 minutes, take the first gel 60-90 minutes into your run to prevent energy depletion.
Hydration is Key: Always consume most gels with water to aid absorption and avoid stomach upset, unless using an isotonic variety.
Trial in Training: Never experiment with a new gel flavor or brand on race day to prevent potential gastrointestinal issues.
Strategic Caffeine Use: Save caffeinated gels for later in long runs or races to get a mental and physical boost when fatigue sets in.
Carb Intake Goal: Aim for 30-60 grams of carbohydrates per hour for runs exceeding 90 minutes to sustain performance.
Consider Real-Food Gels: Brands like Huma use real food ingredients, which may be gentler on sensitive stomachs.
Listen to Your Body: Pay attention to how your body reacts to different gels and fueling strategies during training runs.

The Science Behind Energy Gels

When a runner embarks on a long-distance effort, their body primarily uses glycogen, a stored form of glucose in the muscles and liver, for energy. The body's glycogen stores, however, are limited and can become depleted after approximately 90 minutes of continuous exercise. This depletion leads to a feeling known as "hitting the wall," a sudden and overwhelming fatigue. Energy gels are designed to provide a quick and concentrated source of simple carbohydrates, such as maltodextrin and fructose, which are rapidly absorbed into the bloodstream. This replenishes the body's glycogen stores, allowing the athlete to sustain their pace and performance. The goal is to fuel before the tank runs empty, proactively maintaining energy levels rather than waiting for fatigue to set in.

A Breakdown of Gel Types

Not all energy gels are created equal, with different formulations catering to specific needs during a run. Runners can choose from several varieties based on their preferences, race conditions, and digestive sensitivities.

Classic Gels: These are the standard, dense gels containing simple and complex carbohydrates. They typically require being chased with water to aid digestion and absorption.
Isotonic Gels: Thinner and more liquid than classic gels, isotonic options contain a pre-mixed water and electrolyte solution. The isotonic formula means they can be consumed without extra water, which is convenient during intense efforts or when hydration points are spaced far apart.
Caffeinated Gels: Designed to provide an extra kick, these gels contain varying amounts of caffeine, which can improve focus and performance. They are often used later in a race when fatigue begins to set in, but should be tested in training as they can cause stomach issues for some.
Electrolyte-Enhanced Gels: These contain additional electrolytes like sodium, potassium, and magnesium, which are crucial for replacing minerals lost through sweat, especially during long or hot sessions.
Natural/Real-Food Gels: Using ingredients like maple syrup or chia seeds, these gels are made from more natural sources and can be easier on sensitive stomachs. Brands like Huma are popular in this category.
Hydrogel Gels: Advanced options like Maurten use a biopolymer matrix to encapsulate carbohydrates. This technology is designed for smoother digestion and a more sustained energy release without the need for additional water, though the texture is unique.

How to Use Gels for Optimal Performance

Timing is everything when it comes to fueling with gels. Taking them too late can mean your body has already depleted its reserves, while taking too many too soon can cause gastrointestinal distress.

Fuel Early and Often: For runs exceeding 90 minutes, start taking your first gel 60-90 minutes into the activity. After that, take one gel every 30-45 minutes to maintain a steady flow of carbohydrates.
Practice Makes Perfect: Always test your fueling strategy during training runs. This helps you determine which gels your stomach tolerates best and the ideal timing for your body.
Hydrate with Caution: Unless using an isotonic gel, pair each classic gel with a few sips of water. This dilutes the gel's high sugar concentration and speeds up absorption.
Strategic Caffeine: Use caffeinated gels strategically. Many runners save them for the later stages of a race when they need an extra boost in concentration and energy.
Listen to Your Gut: If you experience stomach upset, consider switching to a different gel type, reducing your intake, or focusing on hydration to see if the issue resolves. The problem can be dehydration-related.

Avoiding Stomach Issues

Experiencing nausea or cramping mid-run is a common fear for many runners. Gastrointestinal distress can often be linked to fueling mistakes, but can be managed with a little planning. The primary causes include a high concentration of simple sugars, which can irritate the gut, and reduced blood flow to the digestive system during intense exercise. Dehydration can also exacerbate these problems. To mitigate these issues, runners can:

Ensure adequate hydration throughout the run, supplementing with electrolyte-enhanced gels or drinks, especially in hot conditions.
Consider using real-food or hydrogel gels, which are formulated to be gentler on the digestive system.
Test different brands and flavors during training to find a gel that works best for your body.
Take gels slowly, over the course of a few minutes, to aid absorption.

Gel Type Comparison Table


Feature	Classic Gels	Isotonic Gels	Caffeinated Gels	Natural/Real-Food Gels
Texture	Thicker, requires water	Thinner, water pre-mixed	Varies by brand	Smooth, often with unique texture (e.g., chia seeds)
Primary Benefit	Quick carbohydrate boost	Rapid energy and hydration	Mental alertness, delayed fatigue	Gentler on the stomach, sustained energy
Example Brands	GU Energy Gels	High5 Energy Gel Aqua, SIS GO Isotonic	GU Roctane, Maurten Gel 100 CAF	Huma Chia Energy Gel, Untapped
Best Used	During long training runs	Hot weather, hydration needs	Late in races, long efforts	For sensitive stomachs, steady energy
Water Requirement	Yes	Not required, but recommended	Varies, usually yes	Varies, usually yes

Finding Your Perfect Fuel

Ultimately, the best gel for any runner is a personal choice based on individual taste, texture preference, and digestive response. The wide variety of options means there is a gel for almost every need, from the classic, fast-acting boost to the advanced, sustained-release hydrogel. The most important rule is to test your chosen gel repeatedly during training, ensuring it works seamlessly with your body before race day. Your ideal fueling strategy might even involve mixing and matching different types of gels, perhaps starting with a non-caffeinated option and introducing a caffeinated one later in the race. For further reading on comprehensive fueling plans, explore advice from a trusted source like Sports Dietitians Australia.

Conclusion

Understanding what gel do runners eat extends beyond simply grabbing a pack off the shelf. It involves understanding the science of glycogen, knowing the different types of gels available, and developing a strategic fueling plan based on personal needs and race demands. By practicing with different gels during training, paying attention to hydration, and listening to your body, you can create a nutrition strategy that maximizes your performance and minimizes the risk of mid-run stomach issues. With the right gel at the right time, you'll be able to power through your next long run or race with confidence.

Frequently Asked Questions

For runs lasting over 90 minutes, the first energy gel should be taken 60-90 minutes into your activity to top off glycogen stores before they are depleted.

No, not all energy gels require water. Isotonic gels are pre-mixed with water and electrolytes and can be consumed without extra fluid. Most classic, non-isotonic gels, however, should be taken with water to aid absorption and prevent stomach upset.

The main difference is the texture and water content. Classic gels are thicker and require water, while isotonic gels have a thinner, more liquid consistency with added water, making them easier to consume on the go.

Caffeinated gels can be beneficial for an extra mental and physical boost, especially later in a race when you feel fatigue. However, they should be tested during training, as some runners experience stomach upset or jitters.

Yes, gels can cause stomach problems, particularly if they have a high sugar concentration, are taken without enough water, or are consumed during intense exercise when blood flow is redirected away from the digestive system.

The recommended intake for marathon runners is 30-60 grams of carbohydrates per hour. Since most gels contain 20-30g of carbs, this translates to roughly one to two gels per hour, after the initial 60-90 minute period.

It depends on the individual. Natural gels often use real food ingredients, which can be gentler on sensitive stomachs and avoid artificial additives. Traditional gels, however, are formulated for fast absorption. Personal tolerance and preference are key.

Hydrogel gels, like those from Maurten, use a special technology to encapsulate carbohydrates in a biopolymer matrix. This allows for smoother digestion and a sustained release of energy, often without the need for additional water.