Intra-Run Fueling: What to Eat, When to Eat, and Why It Matters for Runners
If you’re running longer than 60 minutes, fueling during your run isn’t optional—it’s essential! Whether you’re training for your first half marathon or chasing a new PR, intra-run fueling is not just about staying energized—it’s about maintaining performance, avoiding burnout, and protecting your long-term recovery. It can be the difference between fading in the final miles and finishing strong.
Let’s break down why fueling during your run matters, how carbohydrates power performance, what happens if you skip fuel, and which options are best for runners.
Why Intra-Run Fueling Matters
Your body relies on glycogen (stored carbohydrates in your muscles and liver) as its primary fuel source during long or intense runs. But there’s a catch: glycogen stores are limited, typically lasting around 90–120 minutes before they run dry. The average runner can store about 1,500–2,000 calories worth of glycogen during those 90 to 120 minutes of sustained activity.
Once those stores are depleted, you “hit the wall”… a dreaded crash in energy that makes every step feel ten times harder.
When You Don’t Properly Fuel, Here’s What Happens:
- Glycogen stores get depleted → leaving your muscles without quick energy.
- Blood glucose drops → leading to brain fog, poor coordination, and slowed reaction time.
- Muscle breakdown increases → your body starts converting protein into energy, which delays recovery.
- “Hitting the wall” sets in → you feel sluggish, dizzy, and mentally defeated.
💡 Properly fueling during your run preserves glycogen, maintains blood glucose levels, and delays fatigue—so you can run stronger for longer.
Carbohydrates: The Core of Endurance Fuel
Carbs are the fastest and most efficient energy source during running. They’re easy to break down, quickly absorbed, and essential for both physical and mental performance.
Benefits of Intra-Run Carbohydrates:
- Provide fast, accessible energy
- Support brain function and coordination
- Reduce muscle damage and improve post-run recovery
- Help maintain pace and avoid mid-run crashes
🚗 You wouldn’t drive a car without gas, so why would you run without fueling your body?!
What to Eat During Your Run
There are several types of intra-run fuel, and the best one depends on your preferences, effort level, and distance. All of these options are rich in carbohydrates and are designed to be easily digestible. Just remember that there is no one-size fits all option; everyone runs differently and may require different fueling needs.
Energy Gels
Small packets of concentrated carbohydrates, often 20–25g each.
✅ Pros: Quick to absorb (which provides quick energy), easy to carry, most available with caffeine or electrolytes
⚠ Cons: Can be too sweet or thick for some
Popular brands: GU, Maurten, SiS, Huma (uses fruit puree and chia for a more natural option)
Chews & Gummies
Chewable alternatives to gels that deliver carbs in small bites.
✅ Pros: Easy to portion, great for sensitive stomachs
⚠Cons: Require chewing—may not be ideal during high intensity or in later miles of a long run
Popular brands: Clif Bloks, Honey Stinger Chews, Bonk Breakers, GU Energy Labs
Carb Drink Mixes
Hydration and fuel in one! Most commonly comes as a powder to mix with water—provides carbs, electrolytes, and hydration all in one.
✅ Pros: Easy on the stomach, hydrates and fuels simultaneously
⚠Cons: Requires carrying a bottle or hydration vest
Popular brands: Tailwind, Maurten Drink Mix, Skratch Labs, LMNT
Real Food (Popular with Ultra-Distance Runners)
For longer endurance events, some runners tolerate real foods like bananas, dates, pretzels, sweet potatoes, or even baby food pouches.
✅ Pros: More variety, can feel better and be easier to digest on long, slower runs
⚠Cons: Bulky, less consistent in carbs per serving (you may need to eat more to take in enough carbs), slower to digest at faster paces.
How Much and How Often Should You Fuel?
⏱️ For runs over 60 minutes:
- Start fueling 30–45 minutes into the run
- Then refuel every 30–45 minutes
- 1–2.5 hours: Aim for 30–60g of carbs per hour
- 2.5+ hours: Aim for up to 90g of carbs per hour
🗝 You’ll need to train your gut for that intake level.
🧪 Example: On a 2-hour long run, you might take a gel at 45 minutes, and another gel or drink mix at 90 minutes.
💡 Timing Tip: Start fueling before you feel tired or hungry to prevent your body from playing catch up!
Don’t Forget Hydration & Electrolytes
Sweating depletes electrolytes— especially during warmer weather or longer efforts, replacing sodium, potassium, and magnesium is essential to prevent cramping and dehydration.
Solutions:
- Choose gels or mixes that include electrolytes
- Or supplement with salt tabs or electrolyte tablets (like Nuun or SaltStick)
Train Your Gut, Just Like Your Legs
Fueling during runs takes practice. Many runners don’t experience GI issues because of the product, but because their digestive system isn’t trained to handle fuel while on the move.
What can you do to avoid issues?
- Start with small amounts and build gradually
- Use training runs to test race-day fuel
- Stick to familiar products—never try anything new on race day
Final Thoughts: Train Smart. Fuel Smarter. Finish Stronger
Properly fueling during your run is not just about finishing—it’s about performing your best and protecting your body. It can dramatically impact your performance, mindset, and recovery. By choosing the right fuel for your body that matches your effort level and race length—and by practicing your strategy in training; you’ll run stronger, recover faster, and enjoy every mile a little more.
Tuesday Workout (6.3.25) – Head Over Heels Training says:
[…] a blog post I had written about fueling. That post can be found on the website, linked below. https://headoverheelstraining.com/intra-run-fueling-what-to-eat-when-to-eat-and-why-it-matters-for-r… Over the next few weeks, I’ll begin sharing other posts with (hopefully) helpful information here […]