Ingredients for Energy Gels: A Step-by-Step Guide for Marathoners (2026)

By Ethan Brooks

Updated November 2026

Energy gels are built from a short list of ingredients, and knowing what each one does lets you choose a gel that digests well at race pace and avoid surprises on long runs. This guide walks through the core ingredients for energy gels, explains the role of each, and gives you a simple way to judge a label before you buy a box. By the end, you should be able to read any ingredient panel and know whether it suits your stomach, your race plan and your training.

What Energy Gels Are Designed to Do

An energy gel is a concentrated, portable carbohydrate source. Most marathoners aim to take in roughly 30 to 60 grams of carbohydrate per hour once they are past the first hour of running, and a typical gel packet delivers around 20 to 25 grams. Because the gel is thick, portable and easy to swallow with water, it fits well into a race-day routine. The ingredients determine how quickly the carbohydrate reaches your bloodstream, how your gut tolerates it, and whether the packet adds anything beyond fuel, such as electrolytes or caffeine.

Shopping for one? See our guide: Honey Stinger Energy Gels Review (2026): Pros and Cons.

The Core Ingredients for Energy Gels

Nearly every gel contains some combination of carbohydrates, electrolytes, water, a thickener, flavorings and sometimes caffeine or amino acids. Each category does a different job.

Carbohydrate Sources

Carbohydrates provide the actual energy. Gels typically use one of three main sources:

• Maltodextrin: A glucose polymer that is absorbed quickly and is the most common base in gels. It produces a fairly low sweetness level, which many runners find easier to tolerate in volume.
• Glucose (dextrose): A simple sugar that is absorbed rapidly. It is often combined with maltodextrin.
• Fructose: A simple sugar absorbed through a separate intestinal pathway from glucose. Gels that combine glucose or maltodextrin with fructose in a ratio near 2:1 are designed to use both pathways at once, which can raise the total amount of carbohydrate your gut can absorb per hour.

When you check a label, look for the total carbohydrate per packet and the type of sugars listed. A gel with 25 grams of carbohydrate from maltodextrin alone is different in practice from one with the same total but a glucose and fructose blend.

Electrolytes

Sodium is the electrolyte most relevant to gels. You lose sodium in sweat, and taking in a modest amount during long efforts helps with fluid balance and may reduce cramping risk for some runners. Many gels contain somewhere between roughly 50 and 200 milligrams of sodium per packet. Potassium and magnesium appear in some formulas as well. The amount you need depends on your sweat rate, the heat and your personal tolerance, so the label number is only a starting point.

Thickeners and Texture Agents

Gels need enough body to stay in the packet and flow smoothly when squeezed. Common thickeners include xanthan gum and similar plant-derived gums. These ingredients are generally well tolerated, but some runners notice a heavier feeling in the stomach with high gum content. If you have a sensitive gut, a gel with a shorter ingredient list may sit more comfortably.

Flavorings, Acids and Sweeteners

Citric acid, malic acid or similar acids brighten the taste and can make a sweet gel more palatable. Natural and artificial flavorings are used to create fruit profiles such as orange, lemon-lime or berry. Some gels add sweeteners beyond the main sugars. These matter for taste but usually do not change the energy content in a meaningful way.

Caffeine and Other Performance Additives

Caffeine is one of the most common add-ons. A gel may contain roughly 25 to 100 milligrams per packet, depending on the product. Caffeine can help some runners feel more alert late in a race, but the effect varies, and high doses can cause jitteriness, stomach upset or sleep problems later. Amino acids such as taurine or branched-chain amino acids appear in some formulas, but evidence that they meaningfully improve endurance performance from a gel is limited. Treat these as optional, not essential.

How to Evaluate an Ingredient Label, Step by Step

Use this sequence to compare gels quickly and fairly.

1. Find the total carbohydrate per packet and confirm it is in the 20 to 25 gram range if you want a standard serving.
2. Check the sugar sources. Note whether the gel uses maltodextrin only, glucose plus fructose, or another combination.
3. Look at the sodium content and compare it with your known sweat rate and race conditions.
4. Scan for caffeine. Decide whether you want it, and at what dose, before you test the gel on a run.
5. Review the full ingredient list for thickeners, acids and flavorings you may react to.
6. Count the packets you will need for your race and training schedule, and buy enough to test a few flavors in training.

Matching Ingredients to Your Training and Race Plan

The best gel is the one you can take consistently without stomach trouble. Test any new product during long runs, not for the first time on race day. A gel with a higher sodium or caffeine load may suit a hot marathon but feel excessive on a cool training run. Likewise, a gel with a fructose blend may help you push toward higher hourly carbohydrate intake, but only if your gut has been trained to handle it.

If you are comparing specific brands, the article Science in Sport Isotonic Energy Gels: How to Use Them for Marathon Fueling explains how isotonic formulas fit into a marathon plan, and When to Take Energy Gels: A Marathoner's Timing Guide covers how often to take each packet during a run.

Gel Types Based on Ingredient Focus

Some gels are built around a particular goal. Standard carbohydrate gels suit most runners. Caffeinated gels add a stimulant for late-race focus. Lower-carb or fat-based gels serve athletes following specific dietary approaches. For readers exploring those categories, Top 7 Carb Boom Energy Gels Worth Considering in 2026 and Top 7 Fat Based Energy Gels for Long Endurance Fueling compare products within those groups. If you prefer ingredient-clean options, Top 7 Healthy Energy Gels for Running Worth Considering in 2026 looks at formulas with simpler ingredient lists.

Common Mistakes

• Choosing by flavor alone. A gel you enjoy is only useful if its carbohydrate and sodium levels suit your plan.
• Testing for the first time on race day. Ingredients that feel fine on paper can cause cramps or nausea under race stress.
• Ignoring caffeine. Stacking caffeine from gels, drinks and pre-race coffee can overshoot your tolerance.
• Taking gels without water. Thick gels generally need fluid to digest comfortably.
• Assuming more is better. Taking several packets at once does not speed up absorption and can upset your stomach.

Tips for Using Gel Ingredients Well

• Practice with your race-day gel during at least three or four long runs before the event.
• Match sodium intake to your sweat rate, which you can estimate by weighing yourself before and after a run.
• Take your gel with a few sips of water, and avoid large gulps that can cause bloating.
• If you use caffeine, start with a small dose in training to learn your response.
• Keep a training log noting which flavors and ingredient profiles worked and which did not.

Recommended gear

A few supplies make it easier to test and carry gels effectively.

• Running belt with gel loops: Keeps packets secure and easy to reach mid-run, which helps you stick to your schedule. View on Amazon
• Soft flask for water: Lets you take gels with small sips of fluid, supporting digestion during long efforts. View on Amazon
• Digital kitchen scale: Helps you weigh yourself before and after runs to estimate sweat loss and adjust sodium intake. View on Amazon

FAQ

What is the most important ingredient in an energy gel?

Carbohydrate is the most important, because it supplies the energy. The type and amount matter most, with maltodextrin, glucose and fructose being the common sources.

How much sodium should an energy gel have?

Most gels contain roughly 50 to 200 milligrams per packet. The right amount for you depends on your sweat rate, the heat and your tolerance, so test before race day.

Is fructose in gels better than glucose alone?

A glucose and fructose blend may allow your gut to absorb more carbohydrate per hour than glucose alone, but only if your stomach is trained to handle it. Individual response varies.

Are caffeinated gels safe to use during a marathon?

For most healthy adults, moderate caffeine is generally considered acceptable, but total intake from all sources should be considered. If you have a heart condition, anxiety, or take medications, consult a doctor before using caffeine during exercise.

Do energy gels need to be taken with water?

Usually yes. Taking a gel with a few sips of water helps it digest and reduces the chance of stomach discomfort.

Can I make my own energy gel at home?

Homemade gels are possible using maltodextrin, honey or syrup, salt and water, but texture and sugar concentration are harder to control. Test any homemade recipe thoroughly in training.

How many gels should I take in a marathon?

Many marathoners take one gel every 30 to 45 minutes after the first hour, though needs vary by pace, body size and fueling strategy. A coach or sports dietitian can help tailor your plan.

Are gels with added amino acids necessary?

No. Evidence that added amino acids improve race performance from a gel is limited, so they are optional and should not replace a sound carbohydrate and sodium plan.

Conclusion

The ingredients for energy gels come down to carbohydrate type and amount, sodium, texture agents and optional add-ons like caffeine. Reading a label with those categories in mind lets you compare products on what actually matters for your run. Test your chosen gel in training, adjust based on how your stomach responds, and only then carry it into race day.

About Ethan Brooks

Ethan Brooks is part of our editorial team and reviews and edits our marathon & half-marathon guides, checking product details against manufacturer specifications and owner feedback.