For any run lasting longer than about 90 minutes, your body needs more fuel than it can store on its own. Your muscles hold roughly enough glycogen (stored carbohydrate) to power 90 to 120 minutes of steady running, and once those reserves drop too low, you hit the wall: pace slows, legs feel heavy, and your brain gets foggy. Fueling well before, during, and after a long run keeps that from happening.
What to Eat the Day Before
The goal the day before a long run is to top off your glycogen stores so you start with a full tank. For runs under 90 minutes, eating normally with a carbohydrate-rich diet is enough. For anything longer, a more deliberate carb-loading approach makes a measurable difference in performance.
The standard recommendation is 6 to 12 grams of carbohydrate per kilogram of body weight in the 24 hours before a long effort. For a 70 kg (154 lb) runner, that works out to roughly 420 to 840 grams of carbs across the day. If you’re preparing for a race or an especially demanding effort over 90 minutes, bumping intake to 10 to 12 grams per kilogram and starting the loading process 36 to 48 hours out gives your muscles and liver the best possible glycogen reserves.
In practice, this means meals built around rice, pasta, bread, potatoes, oatmeal, and fruit. Keep fiber and fat moderate so you’re not dealing with digestive issues the next morning. This isn’t the day for a huge salad or a high-fat steak dinner.
Your Pre-Run Meal
Eat a familiar, carbohydrate-focused meal two to four hours before your run. Something like oatmeal with banana, toast with jam, or a bagel with a thin spread of peanut butter works well. The closer you eat to your start time, the smaller and simpler the meal should be. A piece of toast or a few dates 30 to 60 minutes before heading out is fine if you need a small top-up, but avoid anything heavy with a lot of fat or protein that close to running.
The key word here is “familiar.” Race morning is not the time to try a new breakfast. Whatever you plan to eat before a goal race, practice it on your long training runs first.
Fueling During the Run
This is where most runners either underperform or hit the wall unnecessarily. Once you’re running longer than 60 to 90 minutes, you need to start taking in carbohydrates. The general guidelines break down by duration:
- 60 to 150 minutes: 30 to 60 grams of carbohydrate per hour. A single gel every 30 to 45 minutes, or regular sips of a sports drink, covers this range.
- Over 2.5 hours: 60 to 90 grams of carbohydrate per hour. At this intake level, you need a mix of glucose and fructose sources to absorb that much fuel.
That second point matters a lot. Your gut can only absorb glucose through one transport pathway, and it maxes out at about 60 grams per hour. Fructose uses a completely separate absorption pathway. By combining both, say through a gel that uses maltodextrin plus fructose, or by alternating between a sports drink and real food like dates, you can push total absorption up to around 90 grams per hour. Most purpose-built endurance fuels now use a roughly 2:1 ratio of glucose (or maltodextrin) to fructose for exactly this reason.
Start fueling early, within the first 30 to 45 minutes, even if you feel fine. By the time you feel like you need fuel, your glycogen stores are already significantly depleted and it’s hard to catch up.
Practical Fueling Options
Gels are the most convenient option: portable, fast-absorbing, and easy to dose. Energy chews work the same way but give you something to chew on, which some runners prefer. For very long runs or ultramarathons, real food like bananas, rice cakes, pretzels, or boiled potatoes can help break the monotony and provide sodium alongside carbs. Sports drinks pull double duty by delivering carbohydrates and fluid at the same time, though you’ll likely need to supplement with gels if you’re aiming for 60+ grams per hour.
Hydration and Sodium
Dehydration slows you down well before you feel thirsty. The target is to keep body weight loss below 2% during the run, which generally means drinking 200 to 300 ml (roughly 7 to 10 ounces) every 10 to 20 minutes. That adds up to somewhere between 600 ml and 1.2 liters per hour depending on conditions and your sweat rate.
Plain water works for shorter efforts, but on long runs you also need sodium. You lose a significant amount of salt in sweat, and replacing it helps maintain fluid balance and prevent cramping. Aim for 300 to 600 mg of sodium per hour when sweating heavily. Most sports drinks contain some sodium, but if you’re a heavy sweater or running in heat, adding electrolyte tablets or salt capsules can help you hit that range. You can also get sodium from salty snacks like pretzels during ultra-distance efforts.
One thing to watch: highly concentrated sugar solutions empty from your stomach much more slowly than dilute ones. A study comparing glucose solutions found that a concentrated version took over twice as long to leave the stomach compared to a dilute one. Glucose polymer solutions (like maltodextrin-based drinks) empty faster than simple sugar solutions at the same calorie content. The practical takeaway is to avoid chugging thick, sugary liquids. Sip a properly diluted sports drink or take gels with a few swallows of water to keep things moving through your stomach.
Train Your Gut
If you’ve ever felt nauseous, bloated, or crampy from eating during a run, that’s not a sign you “can’t eat while running.” It’s a sign your gut hasn’t adapted yet. The gut is trainable, and the research on this is clear.
Your intestines increase the number of carbohydrate transporters in response to regular carbohydrate intake. Animal research suggests that increasing dietary carbohydrate from 40% to 70% of calories can double the number of glucose transporters in the intestinal lining within two weeks. Changes in gastric emptying (how fast food leaves your stomach) can show up in as little as three days of practice. A 28-day study in cyclists showed that training regularly with high carbohydrate intake increased the body’s ability to use ingested carbs during exercise.
The practical advice: practice your race-day fueling strategy on your long training runs. Start with smaller amounts if you’re not used to eating while running, maybe 30 grams per hour, and gradually increase over several weeks. Practice with the exact products you plan to use on race day. Your stomach will adapt, and by the time you toe the start line, taking in 60 to 90 grams per hour will feel routine instead of risky.
Recovery Fueling After the Run
What you eat in the first 30 to 60 minutes after a long run has an outsized effect on how quickly your muscles recover. Glycogen resynthesis, the process of restocking your fuel stores, happens fastest in that window. The recommended approach is a snack or meal with carbohydrates and protein in a 3:1 or 4:1 ratio. That translates to about 1.2 to 1.5 grams of carbohydrate per kilogram of body weight plus 0.3 to 0.5 grams of protein per kilogram.
For a 70 kg runner, that’s roughly 85 to 105 grams of carbs and 20 to 35 grams of protein. A chocolate milk and a banana, a smoothie with fruit and yogurt, or rice with chicken all fit the bill. If your stomach is uneasy after a hard effort, a recovery drink can be easier to get down than solid food.
Beyond the immediate window, your daily protein intake matters for ongoing muscle repair. Endurance athletes generally benefit from 1.4 to 2.0 grams of protein per kilogram per day, spread across meals every three to four hours. During heavy training blocks, bumping toward the higher end of that range supports recovery between sessions.
Putting It All Together
A fueling plan for a two-and-a-half-hour long run might look like this for a 70 kg runner: a bowl of oatmeal with banana and honey three hours before (roughly 80 to 100 grams of carbs), a gel at the 30-minute mark and every 30 minutes after that (targeting 60 grams of carbs per hour using a glucose-fructose product), 200 to 300 ml of water or electrolyte drink every 15 minutes throughout, and a recovery smoothie with 90 grams of carbs and 25 grams of protein within 30 minutes of finishing.
Everyone’s tolerance and preferences differ, so treat these numbers as starting points and adjust based on how your body responds. The single most important thing you can do is rehearse your fueling strategy in training. Runners who nail their nutrition on race day almost always did so because they practiced it dozens of times before.