Everything New Runners Need to Know About Fueling

As a runner, proper fueling is a key factor that impacts your energy levels, performance, and how quickly you recover. Without the appropriate fuel at the right time, you may experience energy crashes, muscle soreness, or delayed recovery—all of which can hinder your progress. But with the right fueling strategies and a little planning, you can dial in your nutrition to make your food work for you, no matter which distance you’re looking to tackle.

Muscle glycogen—the stored form of carbohydrates (carbs)—can fully deplete in about two hours of moderate-intensity exercise, assuming stores are full at the start. To maintain energy and optimize performance, runners must prioritize fueling before, during, and after runs, especially on longer sessions. Unlike daily nutrition, sports fueling emphasizes low-fiber and low-fat, easy-to-digest carbs to help prevent gastrointestinal (GI) distress such as abdominal cramping, bloating, diarrhea, and nausea.

As a board-certified sport dietitian, I’ve worked with hundreds of athletes ranging from their first 5K to 100-mile events. Everyone has unique nutritional needs based on the duration, the intensity, their individual sweat rate, their gastrointestinal sensitivity, and their taste bud preferences. Still, there are a few fundamental principles that hold true for nearly all runners. Here, we’ll explore fueling fundamentals to enhance your performance and make your runs more enjoyable.

Pre-Run Fueling

Fueling before a run ensures you come prepared with the energy to perform your best, whether it’s an easy-pace training run or a race day.

5K–10K Nutrition

If the run is less than 45 minutes, you don’t need to fuel before or during the run, though be sure to stay on top of your hydration (see chart below). For runs lasting longer than 45 minutes, aim to have a small, easy-to-digest snack 1 to 1.5 hours beforehand. Choose low-fiber, low-fat options to ensure quick digestion and reduce GI issues.

Pre-workout examples containing 25 grams of carbs:

• ½-¾ cup cooked rice
• 10 saltine crackers
• 1 medium banana
• ½ cup applesauce
• English muffin
• 6 ounces low-fat yogurt

13.1 and Longer

Longer runs that last 75 minutes or more require more strategic pre-fueling. Carbohydrate loading the day before (in which you increase carbs and reduce fat) can maximize muscle glycogen, and some carb sources are smarter picks than others.

Carb-rich food examples include:

• Baked potato instead of French fries
• Pretzels instead of chips
• A bagel or pancakes instead of a muffin
• Pasta with red sauce instead of Alfredo sauce

On the morning of a long run or race, plan to eat breakfast 2 to 2.5 hours before the start, focusing on easily digestible carbs. Pro tip: Test drive this meal repeatedly during training. 

If you can’t eat 2–2.5 hours before the run, have a small snack 30–90 minutes before. Avoid nut butter less than 60 minutes before the start, as it can cause GI discomfort in some runners.

Pre-long run meal (2–2.5 hours before):

• Oatmeal topped with banana and honey
• Bagel with a light cream cheese, jam, and/or nut butter spread
• Banana with non-fat yogurt and orange juice
• A smoothie made with fruit, yogurt, and oats

Pre–long run snack (30–90 minutes before):

• 8–12 saltines with 1 tablespoon nut butter
• One rice cake with 1 tablespoon nut butter and 1 tablespoon jam
• One large banana, optional light spread of nut butter
• 1 oz pretzels
• 2–3 large rectangle graham cracker pieces
• Sports bar that is low in fat and fiber
• 90–120-calorie sports drink (22.5–30g carbs)

Fueling During the Run

Fueling during a run helps sustain performance and delays fatigue.

5K–10K

For runs under 45 minutes, extra fueling is typically unnecessary. However, on a hot day when hydration becomes a concern, carry a water bottle in a hydration belt and sip frequently to stay hydrated. If you lose more sweat than a normal workout or than the average person, consider adding a low-carb electrolyte mix to your water.

13.1 and Longer

When you tackle longer distances and run for longer than 75 minutes, fueling becomes even more important to prevent “bonking” or hitting the wall. Start fueling early and often throughout the run. Aim for 30–60g carbs per hour, beginning from the start. Use a properly formulated sport drink (not too concentrated) that mixes to a dilution of 35–42g/20 oz bottle or 40–50g/24 oz bottle. Adjust fluid consumption based on your sweat rate and conditions. For additional nutritional support, test energy gels (20–30g carb/gel) or chews (4–8g carb/chew), but prioritize your sport drink since it provides fluid, electrolytes, and carbs all in one.

Pro tip: One medium gulp equals 1 oz. Plan to take 4-6 gulps every 10–15 minutes, adjusting for individual sweat rate, temperature, intensity, and run duration.

Hydration

Staying hydrated is just as important as fueling. Start each run adequately hydrated without overdoing it, especially when consuming plain water. Regardless of the distance, always carry hydration, and longer runs require extra attention for performance and recovery. Adjust fluid intake based on environmental conditions and individual sweat rate.

Fuel and Hydration Guidelines Based on Run Duration and Intensity

(Note: Carbohydrate recommendations are based on grams per hour, not body weight.)

Post-Run Fueling

Recovery is key to replenishing glycogen stores, repairing muscles, and preparing for your next run. Regardless of your run duration, don’t skip this step.

5K–10K

Within 30-60 minutes, consume a snack with 25–30g of protein and 40–60g of low-fat carbs to kickstart recovery.

13.1 and Longer

Longer runs require a more structured recovery. Aim for 60–90g low-fat carbs and 25–30g protein within 30–45 minutes of finishing. Follow it up with a balanced meal within two hours. If your post-run meal is timely, you can skip the recovery snack.

Recovery snack ideas: 

• 16 oz ultra-filtered low-fat chocolate milk (12g protein/8 oz)
• 6 oz Greek yogurt with strawberries or a banana
• 20g whey or vegan protein powder mixed with milk or almond milk and oatmeal with berries
• Turkey and cheese sandwich
• Scrambled eggs (4 eggs or egg whites) with a bagel and jam

Rehydration

Replenishing lost fluids is critical to recovery, especially after a long, sweaty run. Aim for gradual rehydration over the first six hours, avoid chugging, and take frequent small sips to maximize absorption.

Pro tip: Rehydrate by consuming 20 oz of fluid for every pound lost during exercise over 6 hours.

Final Tips for a New Runner

To avoid pitfalls and set yourself up for success, keep these basics in mind: 

Eat enough: Many new runners fall into the trap of not eating enough calories for the amount of energy they’re expending, especially when they’re training for a half or full marathon. If you’re feeling exhausted and not enjoying your workouts, start tracking your calories in versus calories out to make sure you’re getting enough to eat. You’ll also want to ensure you’re getting the proper amount of protein, carbs, and vitamins to sustain your activity level. If things feel wonky, consult your primary care physician or a dietitian. 

Don’t skip hydration: Your options for hydration are either to prioritize a properly formulated sports drink for hydration and fueling while supplementing with gels and chews, or hydrate with water or water mixed with electrolytes while fueling with gels and chews. Either way, sip early and often. And make sure you only consume gels and chews with fluids, or else it can lead to dehydration and GI distress. There is no one way to fuel and hydrate your runs—it’s best to determine what works best for you through trial and error.  

Avoid sugar substitutes: They may taste sweet but provide no energy and can cause GI issues. New studies even suggest that these sweeteners (sometimes lurking in protein bars) can cause cardiac issues like heart attack and stroke. 

Use caution with caffeine: Many runners get an extra boost from their morning coffee or caffeine-infused gels or drinks, but there can be too much of a good thing. A good rule of thumb is to limit dosage to 2mg per kilogram of body weight. Excess caffeine can cause dizziness, headaches, elevated heart rate, and GI issues. Be mindful of how much you are consuming in general, and make sure to test caffeine during training before adding it on race day.

Nothing new on race day: Run apparel, pacing, fueling, and hydration should be tested before race day. Use training to discover what works best for you and stick to it during the race.

Scale back in the taper: Training volume decreases in the taper; therefore, glycogen stores won’t be as depleted as in a typical training week. Eat and hydrate until satisfied, but avoid stuffing yourself.

Pace yourself: Starting too fast can sabotage your race and deplete glycogen stores prematurely. Pace wisely to finish strong.