When should I consume energy gels?: Your ultimate timing guide for athletic fueling

October 23, 2025 •

4 min read

Your body's glycogen stores can fuel moderate-to-high intensity exercise for approximately 90 minutes before depletion, a point often called 'hitting the wall'. To avoid this performance-crippling fatigue during longer efforts, many athletes strategically supplement with energy gels, which raises the crucial question: when should I consume energy gels? for maximum benefit.

Quick Summary

This guide details the scientific principles behind energy gel timing for endurance athletes. Learn optimal schedules for different training and race scenarios, how to choose the right gel for your needs, and the importance of practicing your fueling strategy during training.

Key Points

Timing is key: For activities over 60-90 minutes, start consuming gels before you feel tired and continue every 30-45 minutes.
Practice in training: Test different gels and timing strategies during your long training runs to avoid stomach issues on race day.
Hydrate properly: Always consume standard energy gels with water to aid digestion and prevent dehydration, especially in hot conditions.
Understand your gels: Choose between classic, isotonic, caffeinated, and electrolyte-enhanced gels based on your activity and personal needs.
Avoid overloading: Space out your gel intake and avoid taking too many at once to prevent energy crashes and stomach discomfort.
Combine and conquer: For very long events, mix and match gels with other forms of nutrition like chews or drinks to prevent flavor fatigue and provide variety.

The Science Behind the Gel

Energy gels are packets of concentrated, fast-acting carbohydrates designed to deliver a quick source of energy to your muscles during exercise. During physical activity, your body's preferred fuel source is glucose, derived from stored carbohydrates called glycogen. While sufficient for shorter efforts, these glycogen stores eventually deplete, leading to a sudden and significant drop in energy. The simple sugars in energy gels, primarily maltodextrin and fructose, are rapidly absorbed into the bloodstream, where they can be quickly converted into energy to replenish your glycogen stores. This provides a vital fuel source that helps sustain performance and delay the onset of fatigue.

How Gels Work in the Body

When you consume an energy gel, the body quickly processes the simple sugars, causing a spike in your blood sugar level. This glucose is then transported to your muscles and organs for immediate use. For this process to be efficient and prevent stomach upset, especially with classic, non-isotonic gels, it is critical to consume them with water. This helps your body dilute and absorb the carbohydrates effectively. Misusing gels, such as taking too many at once or not drinking enough water, can lead to gastrointestinal distress, such as bloating, nausea, and cramping.

Optimal Timing for Energy Gel Consumption

The best time to take an energy gel depends on the duration and intensity of your activity, as well as your individual metabolic rate. Proper timing is a skill that must be practiced and perfected during training to ensure optimal performance on race day.

Before Exercise

For most activities lasting under an hour, energy gels are generally not necessary, as your existing glycogen stores are sufficient. However, some athletes benefit from a gel 10–15 minutes before the start of a longer event or a high-intensity session, especially if they haven't eaten recently. This can provide an immediate boost of blood glucose to kickstart the effort. This strategy is most effective when the activity begins soon after consumption, as taking a gel too far in advance can cause an insulin spike and a subsequent energy crash.

During Endurance Activities

For activities lasting longer than 60–90 minutes, such as a marathon or long-distance cycling, consistent fueling is essential. The general recommendation is to take your first energy gel 60–90 minutes into your workout and then one every 30–45 minutes thereafter. This regular intake keeps your blood sugar levels steady and prevents your glycogen stores from becoming completely depleted. Athletes often aim to consume 30–60 grams of carbohydrates per hour, and a single gel typically contains 20–30 grams, making the every 30–45 minute schedule effective. Listening to your body is also key; if you feel a drop in energy sooner, it may be time for a gel.

For Shorter, Intense Efforts

While not typically needed for a standard 5k or 10k, a gel can be beneficial before a shorter, intense race if you are pushing for a personal best. A gel taken 15–30 minutes before the start can provide a mental and physical edge. However, for a 10k, focusing on pre-race fueling with a solid meal and staying hydrated is often more important than in-race gels.

Creating a Personalized Fueling Strategy

Every athlete is different, and finding the right fueling plan requires experimentation. Here are some key considerations for developing your personal strategy:

Practice during training: Never try a new gel or a new fueling schedule on race day. Use your long training runs to test different brands, flavors, and timing to see what your stomach tolerates and what provides the best energy response.
Hydration is non-negotiable: Most energy gels should be followed by a few sips of plain water to aid absorption and prevent dehydration, which can worsen potential stomach issues.
Avoid combining with other carb drinks: Consuming a gel alongside a high-carbohydrate sports drink can overload your stomach with too much concentrated sugar at once. If using both, alternate between them.
Consider caffeine: Many gels come with added caffeine, which can provide an extra mental and physical boost, especially in the later stages of a long race. Test these in training, as caffeine sensitivity varies.
Mix it up: To prevent flavor fatigue during long events, consider rotating between different gel flavors or using a combination of gels, chews, and drinks.

Comparison of Common Energy Gel Types


Gel Type	Key Features	When to Use	Water Requirement
Classic Gels	Concentrated carbs (maltodextrin, fructose), thicker consistency.	Endurance activities over 60-90 minutes.	Required. Drink with water to aid absorption.
Isotonic Gels	Thinner, water-based formulation, with added electrolytes.	When convenient fueling is prioritized and hydration is a concern.	Optional, but still advisable to stay hydrated overall.
Caffeinated Gels	Contains caffeine for mental alertness and performance boost.	Later stages of long races or during tough stages when a mental lift is needed.	Follow instructions; often requires water depending on formulation.
Electrolyte-Enhanced Gels	Added electrolytes (sodium, potassium) to replace those lost via sweat.	Long, hot-weather sessions or for athletes prone to cramping.	Can be isotonic or require water, check the label.

Conclusion

Knowing when should I consume energy gels? is a critical part of optimizing your performance in endurance sports. By understanding the science of glycogen depletion and the purpose of energy gels, you can time your intake strategically to prevent energy crashes. The golden rule is to start fueling before you feel depleted, typically 60-90 minutes into a prolonged activity, and continue with regular, measured doses every 30-45 minutes. Always pair non-isotonic gels with water and, most importantly, experiment with different types and timings during your training sessions. This practice will ensure your body is prepared for race day, allowing you to perform your best without stomach upset or energy deficits. The right fuel plan, refined through training, can make all the difference in crossing the finish line feeling strong.

Further Reading on Sports Nutrition and Performance: TrainingPeaks - How To Choose an Effective Energy Gel

Frequently Asked Questions

Classic gels are more concentrated and typically require water for optimal digestion, while isotonic gels are thinner and can be consumed without additional water because they already contain fluids.

Most energy gels are formulated for rapid absorption and typically start providing a noticeable energy boost within 5 to 15 minutes of consumption.

For most runners, energy gels are not necessary for a 10k, as your body's stored glycogen is usually sufficient. However, if you're pushing for a personal best, a pre-race gel might be beneficial.

Yes, energy gels are highly recommended for marathons and other endurance events over 90 minutes. A common strategy is 1 gel every 30–45 minutes, resulting in 4–8 gels for a typical marathon.

Overconsumption can cause gastrointestinal distress, including bloating, nausea, and cramps. It can also lead to energy spikes followed by crashes if not managed with proper hydration.

This depends on your personal tolerance. Caffeinated gels can enhance alertness and reduce perceived effort, especially late in a race. Test them in training to see how your body responds.

If you experience stomach upset, try an isotonic gel, experiment with different brands or carbohydrate types, or switch to an alternative like chews or a sports drink. Always practice during training to find what works best.