Energy Gels for Runners: When and How to Use Them
Last Update June 17th, 2026 by Etienne Durocher
Many runners spend months preparing for a race but only a few minutes thinking about their fueling strategy.
The result is predictable. Training goes well, fitness improves, confidence grows, and race day arrives. Then somewhere between the halfway point and the finish line, energy levels begin to drop. Pace slows, concentration fades, and what once felt manageable suddenly becomes a struggle.
For many runners, this experience is not caused by poor fitness.
It is caused by poor fueling.
One of the most effective tools available to endurance runners is the energy gel. Used properly, gels provide a convenient source of carbohydrates that help maintain energy levels during long training runs, marathons, and ultramarathons. Used incorrectly, they can lead to stomach discomfort, inconsistent energy, and race-day frustration.
Understanding when and how to use energy gels is one of the simplest ways to improve endurance performance.
The goal is not simply to consume calories.
The goal is to provide your body with a steady supply of usable energy while preserving comfort and performance over long distances.
If you are building your overall training structure, begin with: Marathon Nutrition: Fueling Your Marathon
Why Energy Gels Matter
Carbohydrates are the primary fuel source for moderate and high-intensity endurance exercise.
Although the body stores carbohydrates in the muscles and liver as glycogen, those stores are limited. Depending on body size, training status, and race intensity, many runners begin significantly depleting glycogen stores after approximately 90 minutes of exercise.
When glycogen levels fall too low, runners often experience what is commonly called "hitting the wall" or "bonking."
The symptoms are familiar to many endurance athletes. Legs feel heavy. Pace becomes difficult to maintain. Decision-making becomes harder. Motivation drops. What felt manageable an hour earlier suddenly feels overwhelming.
Energy gels help delay this process by providing rapidly absorbed carbohydrates that supplement existing glycogen stores.
Rather than waiting for energy levels to crash, runners can maintain a more consistent fuel supply throughout the race.
This is one reason fueling has become such a major focus in modern endurance training. As race performances continue improving, athletes are learning that nutrition is no longer an afterthought. It is part of the performance equation.
Thinking in Carbohydrates Per Hour
One of the biggest changes in endurance nutrition over the last decade is the shift away from counting gels and toward counting carbohydrates.
Many runners still ask:
"How many gels should I take during a marathon?"
The better question is:
"How many grams of carbohydrates do I need each hour?"
Current recommendations generally suggest:
Half Marathon: 30–60 grams of carbohydrates per hour
Marathon: 60–90 grams per hour
Ultramarathon: Often 60–120 grams per hour depending on duration, intensity, and gut training
This approach is more accurate because different gels contain different amounts of carbohydrates. One brand may provide 20 grams per serving while another provides over 40 grams.
Focusing on total carbohydrate intake allows runners to build a fueling strategy that matches their individual needs rather than relying on a specific number of gels.
That said, beginners often benefit from a simpler guideline.
For many marathon runners, consuming one gel approximately every 22–25 minutes provides a practical starting point and typically supplies enough carbohydrates to support performance without becoming overly complicated.
As experience grows, runners can refine their strategy by tracking total carbohydrate intake more precisely.
When Should You Start Taking Gels?
One of the most common fueling mistakes is waiting too long.
Many runners wait until they feel tired before reaching for a gel. Unfortunately, by the time fatigue becomes obvious, performance may already be declining.
Fueling works best when it is proactive rather than reactive.
Most runners should begin fueling early in the race, often within the first 20–30 minutes depending on race duration and pre-race nutrition.
This may feel unnecessary because energy levels are usually high early in the event. However, the objective is not to solve an energy deficit after it appears. The objective is to prevent that deficit from developing in the first place.
Think of fueling as maintaining a reservoir rather than refilling an empty tank.
Small, consistent intake generally works better than infrequent large doses.
When Should You Start Taking Gels?
One of the most common fueling mistakes is waiting too long.
Many runners wait until they feel tired before reaching for a gel. Unfortunately, by the time fatigue becomes obvious, performance may already be declining.
Fueling works best when it is proactive rather than reactive.
Most runners should begin fueling early in the race, often within the first 20–30 minutes depending on race duration and pre-race nutrition.
This may feel unnecessary because energy levels are usually high early in the event. However, the objective is not to solve an energy deficit after it appears. The objective is to prevent that deficit from developing in the first place.
Think of fueling as maintaining a reservoir rather than refilling an empty tank.
Small, consistent intake generally works better than infrequent large doses.
Another important piece of this puzzle is: Fueling For A Marathon When Life Is Full
Why Some Runners Experience Stomach Problems
One of the biggest concerns runners have about energy gels is digestive discomfort.
The reality is that gels themselves are not usually the problem.
More often, the issue is that the gut has never been trained to handle the nutritional demands of racing.
Insight
They struggle because their footwear is not aligned with their workload.
Guide Here
During exercise, blood flow shifts away from the digestive system and toward the working muscles. This naturally makes digestion more challenging. Introducing large amounts of carbohydrates on race day without preparation can overwhelm the system.
This is why experienced runners practice fueling during training.
Long runs provide an opportunity to test products, timing, carbohydrate intake, and hydration strategies before race day. What works perfectly for one runner may not work well for another.
Training the gut should be viewed the same way we view training the legs.
Both improve through practice.
If you frequently experience stomach discomfort while fueling, read How To Train Your Gut For Marathon and Ultramarathon Racing. Many digestive issues can be improved with a gradual and consistent training approach.
Should You Take Gels With Water?
In most situations, yes.
Taking gels with water generally improves absorption and reduces the likelihood of gastrointestinal distress.
Many runners make the mistake of consuming gels alongside sports drinks. While this may occasionally work, it can also create a very concentrated carbohydrate solution in the stomach, increasing the risk of bloating, cramping, or nausea.
Water helps dilute the carbohydrates and supports more efficient digestion.
This does not mean sports drinks should never be used. Many athletes successfully combine gels and sports drinks during races. However, the total carbohydrate intake must still be considered.
The more aggressive the fueling strategy becomes, the more important gut training becomes.
Do All Energy Gels Work the Same?
Not necessarily.
Different products vary in:
Carbohydrate content
Texture
Sweetness
Electrolyte content
Caffeine content
Ingredient sources
Some runners prefer thicker gels such as Maurten or GU. Others prefer more liquid products such as SIS. Athletes with sensitive stomachs may prefer products containing fewer ingredients or alternative carbohydrate sources.
The best gel is not necessarily the most popular one.
It is the one your stomach tolerates consistently while providing the fuel you need.
This is why experimentation during training is so important.
Race day is not the time to try something new.
What Marathon and Ultramarathon Running Has Reinforced
One lesson becomes increasingly obvious as race distances increase.
Fueling mistakes become more expensive.
A small nutritional error in a 10K may be barely noticeable. The same mistake in a marathon can cost significant time. During an ultramarathon, poor fueling can derail an entire race.
Over the years, I have seen athletes spend countless hours preparing physically while giving minimal attention to nutrition. The athletes who perform most consistently are often the ones who treat fueling as seriously as training.
They practice it.
They refine it.
They learn what works.
Most importantly, they understand that nutrition is not separate from performance.
It is performance.
Practical Tips
If you are new to energy gels, begin by practicing during long runs rather than waiting for race day. Start with a conservative strategy and gradually increase carbohydrate intake as your gut adapts.
Focus on total carbohydrates per hour rather than the total number of gels consumed. This provides a more accurate framework for race nutrition.
Take gels consistently rather than waiting for fatigue to appear. Early fueling generally produces better results than trying to recover from an energy deficit later in the race.
Finally, remember that hydration and fueling work together. Even the best fueling strategy can be compromised if hydration is neglected.
Next, learn how this affects: Why Most Runners Go Out Too Fast
A Coach's Perspective
One of the most common patterns I see among marathon runners is that fueling is often treated as a secondary concern until something goes wrong.
Athletes spend months building fitness, completing workouts, and preparing for race day. Then they approach nutrition with guesswork. Unfortunately, endurance performance is rarely forgiving when it comes to poor fueling decisions.
The good news is that fueling is highly trainable.
Most runners can dramatically improve race-day nutrition simply by practicing during training and developing a structured plan.
You do not need a perfect strategy.
You need a tested strategy.
The runners who consistently finish strong are rarely the athletes making dramatic adjustments during races. They are the athletes executing a plan they have already practiced many times.
Final Thoughts
Energy gels remain one of the simplest and most effective fueling tools available to endurance runners.
When used correctly, they help maintain energy levels, support performance, and reduce the likelihood of hitting the wall during long races.
The key is not simply carrying gels.
The key is understanding how much carbohydrate your body needs, practicing your strategy in training, and developing a plan that works for your individual physiology.
If there is one lesson to take from this article, it is this:
Do not wait until race day to learn how to fuel.
Train your nutrition the same way you train your running, and you will give yourself the best possible chance of finishing strong when the race becomes most demanding.
