Ever bonked on a long run and wished you had a better fueling strategy? 

That wall-hitting, energy-draining experience where your legs suddenly feel like lead and every step becomes a struggle is something most endurance runners know all too well. 

The good news? It’s largely preventable with proper fueling.

Energy gels for running have become one of the most popular and effective fueling options for endurance athletes, and for good reason. They’re portable, convenient, and designed specifically to provide quick-acting carbohydrates when your body needs them most during long-duration activities.

But here’s what many runners get wrong: they either avoid gels entirely because they seem “too processed,” or they use them incorrectly and end up with GI distress that makes them swear off gels forever. Neither approach serves your performance goals.

In this guide, we’ll cover what energy gels actually are, how they work to fuel your runs, when and how to use them properly, how to choose the best options for your needs, and practical tips to avoid the stomach issues that give gels a bad reputation.

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What Are Energy Gels?

In simple terms, energy gels are concentrated carbohydrate supplements designed to provide quick, easily digestible fuel during endurance activities. Think of them as portable energy that you can carry and consume without breaking stride during long runs, races, or intense training sessions.

Most energy gels contain a strategic blend of ingredients designed for rapid absorption and sustained energy:

• Simple carbohydrates: Glucose, maltodextrin, and fructose in various combinations
• Electrolytes: Sodium and potassium to replace sweat losses
• Optional caffeine: 25-50mg for performance boost and mental alertness
• Flavor and texture agents: To make them palatable during exercise

The primary purpose of energy gels is to serve as portable fuel for endurance activities lasting longer than 60-90 minutes. This timeframe is important because your body stores enough glycogen (stored carbohydrate) in your muscles and liver to fuel approximately 90 minutes of moderate-intensity exercise.

What are energy gels designed to do that other foods can’t? 

They provide a concentrated dose of rapidly available carbohydrates in a form that’s easy to carry, consume on the move, and digest during exercise when your digestive system is operating under stress. 

Unlike solid foods that require more energy and blood flow to digest, gels are formulated to be processed quickly even when blood flow is prioritized to working muscles.

Energy gels aren’t meant to replace regular meals or serve as everyday snacks. They’re specialized sports nutrition products designed for the specific demands of endurance exercise when convenience, rapid absorption, and portability are paramount.

How Energy Gels Work During Running

Understanding how energy gels for running work physiologically helps explain why they’re so effective for endurance performance and why timing matters so much for optimal results.

During running, your muscles primarily use glycogen (stored carbohydrates) and fat for fuel. Although the body can continually expand its fat stores, the rate at which it mobilizes that fat for energy is relatively slow. Glycogen can be rapidly converted to energy, making it essential for maintaining pace during moderate to high-intensity efforts.

The glycogen problem: Even well-trained, well-fueled athletes typically have enough muscle and liver glycogen to sustain 90-120 minutes of running at marathon pace; however, once these stores become depleted, your body must rely more heavily on fat oxidation, which forces you to slow down significantly—this is the physiological basis of “hitting the wall.”

Energy gels work by providing external carbohydrates that can be rapidly absorbed and delivered to working muscles via your bloodstream. 

This helps:

• Maintain stable blood glucose levels during long efforts
• Provide immediate fuel source to delay glycogen depletion
• Support both physical and mental performance
• Extend your ability to maintain goal pace

The carbohydrate composition of energy gels is specifically designed for optimal absorption during exercise. Many gels use glucose and fructose combinations because these sugars use different transport mechanisms in your intestines. 

This dual-pathway approach can increase total carbohydrate absorption rates from about 60 grams per hour with glucose alone to potentially 90+ grams per hour with glucose-fructose blends.

When consumed properly with adequate water, the carbohydrates in energy gels are typically absorbed and available to your muscles within 15-20 minutes. This is why experienced runners start fueling before they feel like they need it, rather than waiting until energy levels begin to decline.

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How to Use Energy Gels for Running

Knowing how to use energy gels properly can make the difference between a performance boost and a stomach disaster. The key is strategic timing, proper hydration, and practicing your fueling plan during training.

Timing Guidelines

Start your first gel 45-60 minutes into your run, before you feel like you need it. This proactive approach ensures carbohydrates are available when your glycogen stores begin to deplete.

Continue taking gels every 30-45 minutes throughout your run, with exact frequency depending on:

• Your pace and intensity
• Body size and individual tolerance
• Environmental conditions
• Length of your run or race

The cardinal rule: Always take energy gels with water. 

Most gels are hypertonic (more concentrated than body fluids), so taking them without water can draw fluid into your digestive tract, potentially causing cramping or nausea. Plan to consume 4-6 ounces of water with each gel.

Tailoring Your Strategy

Long training runs (90+ minutes):

• Practice your race-day fueling strategy
• One gel every 45 minutes with water
• On a 90 to 120 minute run, this usually works out to  2-3 gels total (but will depend on the person)

Marathon races:

• Begin fueling 30-45 minutes into the race
• One gel every 30-45 minutes
• Typically means 4-6 gels total depending on finish time

Ultra-distance events:

• Combine gels with other fuel sources so that you don’t get tired of them
• Plan on fueling more frequently
• Extra attention to hydration and electrolyte replacement

Critical Usage Points

Never experiment on race day. Your digestive system needs time to adapt to processing concentrated carbohydrates during exercise. Individual tolerance varies significantly between different gel formulations.

Coordinate with aid stations during races. Plan to take gels shortly before reaching water stations so you can immediately follow up with proper hydration.

Practice opening packages while running during training. Some packages are easier to open than others, and fumbling with a gel during a race can disrupt your rhythm.

Choosing the Best Energy Gels for Runners

Determining the best energy gels isn’t about finding one universally superior product—it’s about identifying which characteristics matter most for your individual needs and physiological responses.

Key Considerations

Carbohydrate content per gel:

• Most contain 20-30 grams of carbs (80-120 calories)
• Lower amounts (20-22g) may be easier to digest
• Higher amounts (25-30g) provide maximum fuel density
• Choose based on body size, pace, and individual needs

Glucose and fructose ratios:

• 2:1 or 3:1 glucose-to-fructose ratios can increase absorption
• Single-glucose formulations better for fructose-sensitive runners
• Higher absorption potential vs. individual tolerance trade-off

Electrolyte content:

• Some contain meaningful sodium (100-200mg per gel)
• Others have minimal electrolytes
• Consider your sweat rate and other electrolyte sources

Caffeine options:

• Caffeinated gels: 25-50mg (half cup of coffee equivalent)
• Benefits: Enhanced performance, mental alertness, reduced perceived exertion
• Use strategically (final marathon gel, challenging ultra segments)
• Consider total daily caffeine intake

Additional Factors

Texture and flavor preferences significantly impact your willingness to consume gels when you need them most. Options range from thick and syrupy to more liquid consistency, with flavors from fruity to chocolate to unflavored varieties.

Dietary compatibility includes vegan, gluten-free, organic, or artificial ingredient-free options for runners with specific requirements.

Package design affects usability during running. Look for easy-open tabs, packages that don’t require scissors, and sizes that fit in running belts or pockets.

The best energy gels are ultimately the ones you can tolerate well, enjoy consuming, and find convenient to use during your specific running activities. This requires experimenting with several brands during training to identify your preferences.

Energy gels are just one piece of your sports nutrition puzzle. For a comprehensive look at other performance-supporting supplements, read our Ultimate Guide to Sports Nutrition Supplements for Endurance Athletes.

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Tips for Using Energy Gels Without GI Issues

Many runners avoid energy gels because they’ve experienced stomach problems, but most GI issues are preventable with proper usage techniques.

Essential Guidelines

Always consume with adequate water. Take 4-6 ounces of water immediately after each gel and continue sipping over the following 10-15 minutes. This prevents the concentrated gel from drawing water into your digestive tract.

Avoid mixing with carb-containing sports drinks. This creates an overly concentrated solution that can overwhelm your digestive system. Use electrolyte-only drinks with gels, or alternate between gels with water and sports drinks without gels.

Start with smaller doses if sensitive. Try half a gel every 20-25 minutes instead of whole gels every 45 minutes. The more frequent, smaller doses may be easier to process while providing similar total carbohydrate intake.

Training and Adaptation Tips

Experiment during training runs:

• Test different brands and formulations
• Give yourself several weeks to identify preferences
• Individual tolerance varies significantly between products

Don’t take on empty stomach:

• Have some food beforehand (banana, toast)
• Helps buffer concentrated carbohydrates
• Reduces likelihood of stomach upset

Practice consistently:

• Your digestive system adapts to processing carbs during exercise
• More training practice = better race-day tolerance
• Consistency is key for adaptation

Storage and Timing Considerations

Mind the temperature: Very cold gels are hard to squeeze; hot storage makes them thick and unpalatable. Store at moderate temperatures when possible.

Maintain overall hydration: Dehydration impairs carbohydrate absorption and increases GI distress likelihood. Stay consistently hydrated throughout your run.

If issues persist despite proper usage, try gels with different carbohydrate sources, simpler formulations, or food alternatives like dates or bananas for comparison.

If you experience digestive issues during running beyond gel-related problems, our blog post Runner’s Stomach: Why It Happens and What You Can Do covers additional causes and solutions.

Fuel Smarter, Run Stronger

Energy gels for running represent one of the most convenient and effective fueling strategies available to endurance athletes. When used properly, they help maintain energy levels, delay fatigue, and support peak performance during long training runs and races.

The key to success lies in understanding that energy gels are specialized tools designed for endurance activities lasting longer than 90 minutes. They’re not magic bullets or everyday snacks, but they excel at providing portable, rapidly absorbed fuel when you need it most.

Success with energy gels requires:

• Understanding proper timing and hydration techniques
• Experimenting during training to find what works for you
• Patience as your digestive system adapts
• Realistic expectations about their role in your fueling strategy

Remember that the best energy gels are the ones that work for your individual physiology and preferences. The tips in this post are all quite general, and it takes time to find the combination of energy gels that works for you and your training and race day goals.

When you fuel smarter, you run stronger. Proper fueling isn’t about copying someone else’s strategy—it’s about understanding the principles and adapting them to your unique needs and goals.

Ready to dial in your fueling strategy for better performance? If you want personalized guidance on optimizing your race-day nutrition and long-term performance goals, I’m here to help. 

Inside my 1:1 coaching program, we’ll create a comprehensive fueling plan that works with your individual preferences and supports your running goals. 

Apply for coaching today and let’s take your endurance performance to the next level.