How to Fuel Properly During Long Runs

Most runners nail their training paces but completely miss the mark on nutrition. You can have the best fitness of your life and still fall apart at mile 18 because you waited too long to eat or drank water without any electrolytes. Long run fueling is a skill. It takes practice, just like your tempo runs.

This guide breaks down what actually works for fueling during long runs, from what to eat before you head out, to what to take mid-run, to how hydration fits into the picture.

Why Fueling During Long Runs Is Different

Short runs don't ask much from your body's fuel stores. Go out for 30 to 45 minutes and your glycogen reserves handle it just fine. But once you pass the 60 to 75 minute mark, things change fast.

Your body stores roughly 1,800 to 2,000 calories of glycogen in your muscles and liver. At a moderate running effort, you burn through 400 to 600 calories per hour. Do the math and you'll see why so many runners hit the wall, especially during marathon-distance efforts. Without replacing carbohydrates mid-run, you're essentially running your car without gas.

The goal of long run fueling is simple. Replace carbohydrates before your glycogen runs out, keep your fluid and electrolyte levels balanced, and train your gut to handle food and drink while you're moving.

What to Eat Before Your Long Run

Your pre-run meal sets the foundation for everything that follows. Eating the right foods 2 to 3 hours before your long run tops off your glycogen stores and prevents starting in a deficit.

Here's what to focus on before heading out:

• Carbohydrates first. Oatmeal, toast, a bagel, or rice are all solid choices. Aim for 1 to 4 grams of carbs per kilogram of body weight, depending on your run length and intensity.
• Moderate protein. A small amount of protein slows digestion slightly and keeps you feeling stable. Think peanut butter on toast or a small serving of Greek yogurt.
• Low fat and fiber. Both slow gastric emptying and increase the risk of GI issues on the run. Skip high-fiber cereals, greasy foods, and anything heavy.
• Hydration. Drink 16 to 20 ounces of water in the hour leading up to your run. Starting even slightly dehydrated tanks your performance faster than you think.

If you're running first thing in the morning, a smaller snack 30 to 60 minutes before works too. A banana, a few crackers with nut butter, or even a sports drink can get you started without a full meal.

Mid-Run Fueling: Carbs, Timing, and Delivery

This is where most runners either overthink it or ignore it completely. Mid-run fueling is non-negotiable for runs over 75 to 90 minutes.

How Many Carbs You Actually Need

Research is pretty clear on this. For runs lasting 1 to 2.5 hours, aim for 30 to 60 grams of carbohydrates per hour. For efforts beyond 2.5 hours, you can go up to 90 grams per hour if you're using a mix of glucose and fructose sources. These two sugars use different transporters in your gut, so combining them lets you absorb more carbs without GI distress.

A single energy gel typically provides 20 to 25 grams of carbs. A sports chew packet gives you around 20 to 24 grams. A banana offers about 27 grams. So for a 2-hour long run, you'd need roughly 2 to 4 gel packs, depending on your pace and intensity.

When to Take Your First Fuel

Don't wait until you feel tired or hungry. By that point, your blood sugar has already dropped. Take your first fuel at the 45 to 60 minute mark, then repeat every 30 to 45 minutes after that. Set a watch alert if you need to. Most runners forget to fuel when they're in the zone.

Gel, Chews, or Real Food

All three work, but each has its place.

• Gels are fast-absorbing and easy to carry. Best for races and tempo long runs.
• Chews take longer to eat but feel more like food. Good for medium-paced long runs.
• Real food like dates, boiled potatoes with salt, or rice balls work well for ultra-distance training runs where your pace is slower and your gut has more time to process.

Training your gut matters a lot here. Practice taking in fuel during training runs so race day doesn't catch your stomach off guard. If you want to go deeper on race-day nutrition timing, check out this guide on race day fuel vs training fuel for a more detailed breakdown.

Hydration and Electrolytes on Long Runs

Water alone isn't enough for runs over an hour. You lose sodium, potassium, magnesium, and chloride through sweat. Replacing fluid without replacing these electrolytes leads to hyponatremia, which is when sodium levels drop too low. It causes nausea, confusion, and in severe cases, serious medical problems.

Here's a basic framework for long run hydration:

• Drink 4 to 8 ounces of fluid every 15 to 20 minutes during your run.
• Use an electrolyte drink or add electrolyte tabs to plain water for anything over 60 minutes.
• Aim to drink to thirst rather than forcing fluids. Overdrinking is just as problematic as underdrinking.
• On hot days or if you're a heavy sweater, increase your sodium intake. Salt capsules or high-sodium sports drinks help.

Sweat rates vary widely between athletes. Some runners lose less than a liter per hour while others lose closer to two liters. Knowing your sweat rate helps you personalize your plan. For more on electrolytes and performance, this article on electrolyte balance for runners and triathletes covers it well.

Building a Long Run Fueling Plan

Putting it all together looks like this for a 3-hour long run:

• 2 to 3 hours before: Full carb-focused meal with moderate protein.
• 30 to 60 minutes before: Light snack or sports drink if needed.
• Mile 6 (about 60 minutes in): First gel or chew, 20 to 25 grams of carbs.
• Every 30 to 45 minutes after: Repeat fueling, rotating flavors to avoid palate fatigue.
• Every 15 to 20 minutes: Small sip of water or electrolyte drink.
• Post-run within 30 minutes: Carbs and protein to kick off recovery.

One key habit: always practice your race-day fueling strategy on long runs. Never try a new gel, drink, or food for the first time on race day. Explore the half-marathon race poster collection or the marathon poster collection at Map Medal to commemorate the races where all this training pays off.

The Bottom Line

Long run fueling comes down to three things: getting enough carbohydrates before glycogen runs out, staying on top of hydration with electrolytes, and training your gut to work with you. Nail all three and your long runs become more consistent, your recovery improves, and your race performances follow.