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For many people, running a marathon is the ultimate bucket list accomplishment. Making it to the finish line is rewarding and empowering — no matter how long it takes.

But running 26.2 miles, plus the weeks and months spent training, requires some high-quality fuel. Here’s what runners should know about fueling their bodies before, during, and after a marathon.

Why Nutrition Matters for Marathoners

“Nutrition is the base of all training, conditioning, and recovery,” according to Mike DiBiasi, MS, RD, LDN, director of sports performance nutrition, UPMC Sports Medicine. Consistent and appropriate amounts and types of carbohydrates, protein, and healthy fats are essential to build and repair muscle. If you don’t provide the right fuel and fluids, you’ll break down muscle and deplete glycogen (stored carbohydrates) faster, he says.

The proper diet can help you get stronger, run longer, and recover faster. But poor nutrition can cause issues that can affect training and impair performance. These can include:

• Dehydration.
• Faster fatigue and feeling like running is harder than usual.
• Higher risk of injury, joint pain, or burnout.
• Problems falling asleep or poor sleep quality, which affect performance.
• Reduced energy stores, limiting how far or for how long you can run.
• Slower recovery after training or the race.

Whether this is your first race or you’re an experienced marathoner, you’ll get more out of your training if you’re consistent about:

• Eating enough calories.
• Getting the right amounts of carbs, protein, and fat.
• Hydrating your body.
• Planning your meals and snacks to get the right nutrients at the right times.

Fuel Needs for Marathon Training

The best fuel comes from a balanced, whole-food diet. It provides high-quality complex carbohydrates, protein, healthy fat, and other essential nutrients you need to go that extra mile.

Eating carbs during marathon training

Carbohydrate-rich foods provide fuel in the form of instantly available glucose in your blood and glycogen stored in your muscles and liver. Your carbohydrate needs depend on your weight and exercise length and intensity.

Sports nutritionists recommend eating approximately 3 to 5 grams of carbs per pound of body weight each day. That means a 150-pound person should consume at least 450 to 750 grams of carbs spread across meals and snacks.

Note that the lower end of this range is fine if you’re running for about one hour. The higher end is appropriate for moderate to high-intensity workouts lasting multiple hours.

To meet those needs, fill half your plate at each meal with these carbohydrate-rich foods:

• Beans (legumes) like lentils, chickpeas, kidney, black, and pinto beans.
• Fruits and vegetables.
• Milk and yogurt.
• Starchy foods like potatoes, corn, peas, winter squash, and white rice.
• Whole grains like oatmeal, shredded wheat, whole grain bread, whole grain pasta, brown rice, and quinoa.

You can also try various carbohydrate-rich energy gels or chews to fuel your longer training runs. You may tolerate or prefer certain brands or ingredients to others. Get some carbs every 45-60 minutes after your first hour of running.

Eating protein during marathon training

Marathon runners need protein to build and repair muscles — but more isn’t necessarily better. Most people need 0.7 to 0.8 grams of protein per pound of body weight. A 150-pound person should aim for 100 to 120 grams of protein per day.

To get the most muscle-building benefit, eat or drink protein-rich foods immediately after or within two hours after a workout. And spread protein out every three to five hours throughout the day.

These are all excellent sources of protein for marathoners:

• Beans, tofu, or tempeh.
• Dairy foods like Greek yogurt and milk.
• Meat, poultry, or fish.
• Nuts, nut butter, and seeds.
• Protein powders, drinks, or bars.

Eating fat during marathon training

Fat is essential, but eating heavy, greasy, high-fat foods too soon before a run may cause digestive discomfort. Ideally, aim for small amounts of healthy fats with meals and snacks from foods like:

• Avocados.
• Fatty fish like salmon or sardines.
• Nuts and nut butter.
• Olive oil.
• Seeds like chia, flax, pumpkin, or sunflower.

Fitness apps are great for calculating and tracking these calorie and nutrient goals. Many are free and do a good job of closely estimating your needs.

How to Hydrate During Marathon Training

Runners must stay ahead of dehydration, so drink early and often, especially when it’s hot outside. Water is great for short runs of less than one hour. But for long training runs and the 26.2-mile race, you’ll need fluids with electrolytes like sodium and potassium plus glucose.

“If you’re new to running a marathon, you should develop a specific hydration plan weeks or months before race day,” says DiBiasi. “It is important to learn how your body tolerates certain amounts of fluids, electrolytes, and carbohydrates as things change during the race.”

He recommends choosing a sports drink with carbohydrates and electrolytes, or a favorite oral rehydration packet, and tracking these things four to six weeks before your race:

• How much do you drink during a training session?
• How do you feel after drinking it (how well do you tolerate it)?
• How is your overall performance?

This will help determine the amount of fluid needed and the carb and electrolyte concentration you need and can tolerate.

Eating Before, During, and After the Marathon

Testing your food, fluids, and race-day fuel well before the big day is best. This will ensure you can tolerate everything without stomach or digestion-related problems.

The day before your race:

• Drink lots of fluids — at least 8 ounces of water every one to two hours.
• Eat high-carbohydrate meals and snacks. Fill at least half your plate (or bowl) with carbohydrate-rich foods.
• Get plenty of rest and sleep.

On race day:

• Don’t skip breakfast. Keep it high in carbs with some protein, like cereal with fruit and nuts or almond butter.
• Focus on early hydration. Drink 16 to 24 fluid ounces of an easy-to-consume fluid like water or favorite sports drink three to four hours before the race. To top off, drink 6 to 12 fluid ounces 30 to 60 minutes before the race.
• Keep meals low in fat. It can slow digestion during the race when you want to empty your stomach and quickly absorb fluids and nutrients.
• Stick to lower-fiber foods. Fiber is great, but too much fiber can make you run for the bathroom during the race.
• Try liquids like smoothies, shakes, or 100% fruit juice if you have trouble eating early.

After the race:

• If you can tolerate eating, stick to low-fiber and low-fat carbs. Bananas or other fruit, nonfat chocolate milk, granola bars, or trail mix are good choices.
• It may take a few days to recover fully. Have patience and practice consistency with hydration, regular meals, and plenty of sleep.
• Try juice, smoothies, or ready-to-drink post-workout supplements if you’re feeling too exhausted to eat.

Training for a marathon is a lot of work but also exciting. DiBiasi advises people to take their time, adjust their nutrition and training plan as needed, and not rush the process. Most importantly, listen to your body and eat, drink, and rest as needed.

Learn more about sports performance nutrition at UPMC Sports Medicine or book a consultation.