Emily ParkerBy Emily Parker

Updated November 2026

Energy gels during training can carry you through long runs without the stomach trouble and energy crashes that come from fueling by guesswork. By the end of this guide, you will know when to start taking energy gels during training sessions, how much to take, how to practice with them so your gut adapts, and which mistakes to avoid. The approach works for marathoners building toward a 20-miler and for half marathoners who want a reliable plan for their weekend long runs.

Why Training Is the Time to Use Energy Gels

Most runners think of gels as a race-day tool, but the real benefit of energy gels during training is that you learn how your body responds to them. Race day is the wrong place to discover that a particular flavor makes you queasy at mile 15. Long runs are the right place to test products, dosing intervals, and how you combine gels with water or sports drink.

Shopping for one? See our guide: 6 Best Energy Gels for Half Marathon Training: Top Picks Compared.

Carbohydrate availability is the main reason gels matter. Your body stores only a limited amount of glycogen in muscle and liver tissue. For many runners, that supply is enough for roughly 90 to 120 minutes of steady effort before performance drops noticeably. Beyond that point, taking in carbohydrate during the run helps delay fatigue. Gels are a concentrated, portable way to do that.

Step 1: Decide Which Runs Need Fueling

You do not need to gel on every run. Fuel during training when the run is long enough that your glycogen stores would start to run low, or when you are practicing a race-day strategy.

  • Runs under 60 minutes: Usually no gel needed. Water is sufficient for most people.
  • Runs of 60 to 90 minutes: Optional. Consider a gel if you feel flat or if the run is at a hard effort.
  • Runs over 90 minutes: Plan to take gels. This is where most of your gut training should happen.
  • Race-simulation runs: Always use your planned race-day products and timing, including pre-run fueling.

Step 2: Choose Your Gels Before You Need Them

Pick one or two gel products and use them consistently through the build-up. Switching brands every week makes it impossible to tell what is working. When comparing products, look at carbohydrate content per packet, the carbohydrate type, caffeine content if any, and whether the texture and flavor sit well with you. A useful starting point is a guide such as Running Energy Gels Comparison: 7 Factors to Compare Before You Buy, which walks through those differences in detail.

Carbohydrate blends matter. Gels that combine glucose and fructose are often used because the two sugars are absorbed through different transporters in the gut, which can allow higher total intake without as much gastric distress. Check the label for the blend and the grams of carbohydrate per serving, then compare that to your planned intake.

Step 3: Work Out Your Dosing

A common target for endurance athletes is somewhere in the range of 30 to 60 grams of carbohydrate per hour for efforts longer than about 90 minutes, with higher intakes sometimes tolerated by well-trained guts. Many gels contain around 20 to 25 grams of carbohydrate per packet, so that often means one gel every 30 to 45 minutes. Always confirm the exact carbohydrate count on the package you are using, because it varies by product.

Start lower than your target and build up over several weeks. Your gut adapts over time, and jumping straight to a high intake is a common cause of cramping and nausea.

Sample Intake Progression

Training Phase Typical Run Length Suggested Gel Approach
Early base 60 to 75 minutes Optional, one gel if needed to test
Mid build 90 to 120 minutes One gel every 40 to 50 minutes, with water
Peak long runs 150 minutes or more One gel every 30 to 40 minutes, matching race plan
Race-simulation week Race distance Exact race-day product, timing, and water intake

These ranges are general guidance. Individual needs vary with body size, pace, heat, and how well you tolerate sugar. If you have a medical condition, are pregnant, or take medication that affects blood sugar, speak with a doctor or registered dietitian before changing your fueling plan.

Step 4: Practice Taking Gels While Running

Taking a gel while running at pace is a skill. Many runners struggle with opening the packet, squeezing it out, and swallowing without breaking stride. Practice these steps:

  1. Tear the top of the packet before the run and keep it in a pocket or belt where you can reach it easily.
  2. Take the gel at an aid station or water stop when you first start practicing, then move to running-only intake.
  3. Squeeze a small amount into your mouth, then wash it down with a few sips of water.
  4. Keep your running form steady. Avoid tilting your head back too far, which can cause choking.
  5. Store used packets in your pocket, not on the course, and dispose of them responsibly.

Step 5: Pair Gels With the Right Fluid

Water is usually the right partner for gels. Sports drink with a similar carbohydrate concentration can cause stomach issues when combined with a gel, because the total sugar load becomes high. Test the combination on training runs. Many runners find that taking a gel with a small amount of plain water works best, and that they should sip water regularly across the run rather than drinking large volumes at once.

Heat and humidity increase fluid needs. On hot days, you may need more water with your gels, and you may also need electrolytes. Practice the exact combination you plan to use on race day.

Step 6: Track What Works

Keep a simple log after each long run. Record the product, the number of gels taken, the timing, the fluid, and any symptoms such as bloating, cramping, or nausea. Over several weeks, patterns become clear. If a particular flavor or brand consistently causes trouble, drop it. If a timing schedule works smoothly, lock it in for race day.

Checklist for Training Fueling

  • Gel product chosen and confirmed carbohydrate count per packet
  • Fueling schedule written down, with gel timing in minutes
  • Water or fluid plan matched to temperature and effort
  • Packets stored where you can reach them without stopping
  • Run log updated with symptoms and notes after each session

Common Mistakes

  • Trying a new gel on race day. Always test any product on a training run first.
  • Starting too high. Build your intake gradually so your gut can adapt.
  • Taking gels without water. Concentrated sugar without fluid can cause cramping and nausea.
  • Waiting until you feel tired. Start fueling early, usually within the first 45 to 60 minutes of a long effort, rather than after you bonk.
  • Ignoring the label. Carbohydrate content varies between products, so count what you actually take.
  • Only practicing at easy pace. Test gels at goal race pace, because breathing and stomach comfort change at higher intensity.

Tips for Better Results

  • Keep your gel carrying system simple. A small belt or a few pockets is enough.
  • Take gels at consistent intervals set by a watch alarm or pace split reminder.
  • Use your long runs to test caffeinated gels if you plan to use them on race day, since caffeine affects some runners more than others.
  • Store gels in a cool place. Heat can soften them and make them harder to swallow.
  • If you use a race-day plan from a guide like When to Take Energy Gels: A Marathoner’s Timing Guide, adapt it to your own tolerance rather than following it exactly.

A few simple items make training with gels easier and more consistent.

  • Running belt with gel loops: Keeps packets within reach and off your hips. Look for a belt with two or more secure loops so you can carry your planned number of gels. View on Amazon
  • Hydration vest or handheld bottle: Lets you carry water for taking gels between aid stations. Choose one that fits your long-run distance. View on Amazon
  • Small running pouch: Good for carrying two or three gels on shorter long runs without a full belt. View on Amazon

FAQ

How many energy gels should I take on a long run?

For runs over 90 minutes, many runners take one gel every 30 to 45 minutes, depending on carbohydrate content per packet and personal tolerance. Build up to that amount gradually over several weeks.

When should I take my first gel during a run?

Most runners start within the first 45 to 60 minutes of a long effort. Starting early helps maintain blood glucose, rather than waiting until fatigue sets in.

Can I take energy gels on an empty stomach?

Some people tolerate gels on an empty stomach, but many do better with a light pre-run snack. Test both approaches during training to see what suits your digestion.

Do I need to drink water with energy gels?

Usually yes. Taking a gel with a small amount of water helps it move through your digestive system and reduces the risk of stomach upset.

What if a gel makes me feel sick?

Stop using that product and try a different one with a different carbohydrate blend or texture. Reduce your intake, sip water, and slow your pace. If symptoms are severe or persistent, consult a healthcare professional.

Should I use caffeinated gels during training?

Caffeinated gels can help some runners, but caffeine affects people differently and can cause jitters or sleep problems. Test caffeinated products only during training before using them on race day.

How long before a race should I stop experimenting with gels?

Aim to finalize your product and timing at least two to three weeks before race day. The last few weeks should be used to confirm your plan, not to try new products.

Are gels necessary for a half marathon?

Not always. Many half marathoners finish without gels, especially at moderate paces. If you race hard or run longer than planned, a gel or two can help, so practice with them on long runs before deciding.

Conclusion

Energy gels during training are most useful when you treat them as a practice tool, not just a race-day item. Use long runs to pick a product, build your intake gradually, and pair gels with water. Track what works, and carry that plan into race day with confidence.

Ready to choose one?

Emily Parker

About Emily Parker

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