Ethan BrooksBy Ethan Brooks

Energy gels are not bad for most runners when used as intended. They are a concentrated source of fast-digesting carbohydrate, designed to replace fuel burned during efforts longer than about 60 to 90 minutes. The concerns come mainly from overuse, poor timing, taking them without enough fluid, or relying on them as everyday food.

Why Energy Gels Get a Bad Reputation

Most of the criticism comes from three sources: sugar content, the texture and taste that many people find unpleasant, and digestive trouble during runs. A typical gel packs roughly 20 to 25 grams of carbohydrate into a small pouch, often from maltodextrin and fructose, and that concentration is intentional. The gel is meant to be absorbed quickly while you are working hard, not eaten as a snack at your desk.

Shopping for one? See our guide: Honey Stinger Energy Gels: 8 Best Options for Marathon Fueling (2026).

Problems tend to appear when someone takes gels at the wrong moment, swallows them without water, or uses several in a short window. Gut discomfort, cramping and nausea are the complaints runners report most often, and they usually trace back to these habits rather than to the gel itself. If you have a medical condition affecting digestion or blood sugar, talk with a doctor or a registered dietitian before adding gels to your routine.

The Factors That Decide Whether Gels Work for You

Several variables determine whether a gel helps or causes problems:

  • Effort and duration. Gels are most useful after about 60 to 90 minutes of moderate-to-hard running. For a 45-minute easy run, you almost certainly do not need one.
  • Total carbohydrate per hour. Many marathon plans target 30 to 60 grams of carbohydrate per hour, with higher intakes sometimes tolerated by well-trained athletes. Your gel count should fit inside that target, not on top of it.
  • Fluid intake. Gels pull water into the gut to be absorbed. Taking them with little water is the most common cause of stomach upset. Sip water with each gel rather than waiting for a fluid station.
  • Gut training. Your stomach adapts to fueling with practice. A gel you have never used on a long run is a poor choice for race day.
  • Sugar sensitivity and flavor fatigue. Some runners find the sweetness unpleasant after a few miles. Trying different flavors and brands in training helps you find one you can keep down.

For a clear picture of how many you may need, see How Many Energy Gels for Half Marathon Runners Need: A Step-by-Step Plan and our guide on When to Take Energy Gels: A Marathoner's Timing Guide.

How to Use Energy Gels Safely

Follow these steps during training and on race day:

  1. Start fueling around the 45- to 60-minute mark on long runs, not at the first mile.
  2. Take one gel every 30 to 45 minutes, matching your planned carbohydrate target.
  3. Drink 4 to 6 ounces of water with each gel, more in heat.
  4. Test the exact brand, flavor and timing on at least three long runs before race day.
  5. Stop using gels that cause cramping or nausea, and try a different format such as chews or real food.
  6. Check expiration dates and store gels somewhere cool, away from direct sun.

If you want alternatives to gels, our overview of Alternative to Energy Gels: 8 Fueling Options That Work for Marathoners covers other options, and Energy Chews vs Gels (2026): Which Is Better for Marathon Fueling? compares the two most common formats.

What We’d Use

Gels that are widely available and well known in the running community include the following. Pick the one whose flavor and texture you already tolerate in training.

  • GU Energy Gel: a long-established, widely used option with several flavors and caffeinated versions. View on Amazon
  • Honey Stinger Organic Energy Gel: a choice for runners who prefer honey-based ingredients and a thinner texture. View on Amazon
  • SiS GO Isotonic Energy Gel: a gel designed to be taken without extra water, useful if you dislike carrying a bottle on shorter races. View on Amazon

Can energy gels upset your stomach?

Yes, especially when taken without enough water or in large amounts. Practicing with the same gel during training usually reduces the problem.

Are energy gels healthy?

They are not meant to be a health food. They are a fast, practical carbohydrate source for endurance exercise, and they are not a substitute for balanced meals.

Do you need energy gels for every run?

No. Short and easy runs rarely need fueling. Save gels for long or hard sessions and race day.

Are caffeinated gels safe?

Caffeine affects people differently. Check your total daily caffeine intake, avoid testing new caffeine doses on race day, and consult a doctor if you have heart or blood pressure concerns.

Ready to choose one?

Ethan Brooks

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.