During long runs lasting more than 90 minutes, you need 30 to 60 grams of carbohydrates per hour to maintain energy and avoid hitting the wall. For very long efforts beyond 2.5 to 3 hours, that number climbs to as high as 90 grams per hour. Getting this right makes the difference between finishing strong and dragging yourself through the final miles.
How Much to Eat Based on Run Length
Your fueling needs scale with duration. For runs under 60 minutes, water alone is enough. Once you cross the one-hour mark, your body starts burning through its stored glycogen faster than it can maintain performance, and topping off with carbohydrates becomes important.
For runs between 90 minutes and 2.5 hours, aim for 30 to 60 grams of carbohydrates per hour. This is the range that works for most long training runs and half marathons. Once you push past 2.5 to 3 hours, as in a marathon or ultra, you may need up to 90 grams per hour depending on intensity. At that higher intake level, you’ll likely need a combination of liquids and solid foods to hit your targets without overwhelming your stomach.
When to Start and How Often to Eat
Don’t wait until you feel depleted to start fueling. Begin eating within the first 30 minutes of your run, then take in small amounts every 15 to 25 minutes after that. Spacing fuel into frequent, small doses is easier on your gut than taking in large amounts all at once, and it keeps your blood sugar steadier throughout the effort.
A practical way to think about it: if you’re targeting 60 grams of carbs per hour, that’s roughly 15 grams every 15 minutes. Most energy gels contain 20 to 25 grams per packet, so one gel every 20 to 30 minutes gets you into the right range. Chews, blocks, and drinks can fill the gaps between gels or replace them entirely.
Best Foods and Products for Mid-Run Fuel
The key quality of any mid-run food is that it’s low in fiber, low in fat, and high in fast-absorbing carbohydrates. Fiber and fat slow digestion, which is exactly what you don’t want when your body is diverting blood away from your gut and toward your legs.
Engineered products like energy gels, chews, and sports drinks are popular because they’re designed for quick absorption and easy portability. But real food works too. Bananas, pretzels, white bread with jam, applesauce pouches, fruit snacks, dried fruit, and plain potatoes are all used by marathon and ultramarathon runners. The best option is whichever one you can stomach at mile 18.
If you’re pushing toward 90 grams per hour on very long runs, look for products that combine two types of sugar (often listed as glucose or maltodextrin paired with fructose). Your intestine absorbs these through separate pathways, so combining them lets you take in more total carbohydrate per hour without the bloating and nausea that come from overloading a single pathway. Research on cyclists found that a roughly equal ratio of fructose to maltodextrin produced the least stomach fullness, cramping, and nausea at high intake rates.
Hydration and Electrolytes During Long Runs
Fluid needs vary widely between runners, but a general target is 3 to 8 ounces every 10 to 20 minutes during runs longer than 60 to 90 minutes. The goal isn’t to replace every drop of sweat. It’s to prevent losing more than about 2% of your body weight in water, which is the threshold where performance starts declining noticeably. A 150-pound runner, for example, would want to avoid losing more than 3 pounds during a run.
Sports drinks that contain 6% to 8% carbohydrate pull double duty, contributing to both your fluid and carbohydrate targets simultaneously. If you’re using gels or solid foods for your carbs, plain water works fine for hydration, but you’ll still need electrolytes from somewhere.
Sodium is the electrolyte you lose most through sweat. For runs over 90 minutes, aiming for 700 to 1,000 milligrams of sodium per hour helps prevent cramping, headaches, and that heavy, sluggish feeling that sets in during long efforts. Adding roughly 200 milligrams of potassium and 60 milligrams of magnesium per hour rounds out the picture. If you’re a salty sweater (you notice white residue on your skin or clothes after runs) or running in hot weather, push toward the higher end of that sodium range.
Training Your Gut to Handle Fuel
One of the most common mistakes runners make is trying a fueling strategy for the first time on race day. Your digestive system needs practice handling food during exercise, and the good news is it adapts remarkably well.
Research from the Gatorade Sports Science Institute shows that practicing your race nutrition plan at least once a week during training can significantly improve tolerance within 6 to 10 weeks. This happens because your intestine physically increases its capacity to absorb carbohydrates when it’s regularly exposed to them during exercise. Within just a few days of higher carbohydrate intake, the transporters in your gut lining that move sugar into your bloodstream start multiplying. Longer exposure amplifies this effect.
This is especially important if you normally eat low-carb or follow a restricted diet. Cutting carbohydrates in daily life can actually reduce your gut’s ability to absorb them during a race. If that describes you, including some higher-carb days in your training week helps maintain the digestive machinery you’ll rely on during competition.
Start conservatively. If you’ve never eaten during a run before, begin with small sips of a sports drink or a few bites of banana and gradually increase the volume and frequency over weeks. Your stomach will catch up.
Putting a Fueling Plan Together
For a 2-hour training run, a straightforward plan might look like this: carry two gels and a bottle of sports drink. Take your first gel at 30 minutes, sip the sports drink regularly, and take your second gel around 75 minutes. That gets you roughly 30 to 45 grams of carbs per hour with minimal hassle.
For a marathon (3 to 5 hours depending on pace), the plan scales up. You might carry four to six gels or a mix of gels and chews, alternating with sports drink at aid stations. Starting at 30 minutes and fueling every 20 minutes, you can work up to 60 or even 90 grams per hour if your gut has been trained for it. Some runners carry a small bag of pretzels or a few pieces of banana for variety, which also helps with sodium and potassium.
Whatever combination of foods and drinks you settle on, the non-negotiable rule is to rehearse it in training. Try your exact products, at your exact intervals, during runs at your expected race pace. Your legs aren’t the only thing that needs to be ready on race day.