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How to Fuel a Marathon From Beginning to End

Registered dietitians and nutritionists offer their best marathon fueling tips for before, during, and after the race.

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It’s finally marathon season. Have you nailed down your fueling strategy for 26.2 miles of running? After all, you can’t run on adrenaline alone.

There is no right or wrong way to fuel for a marathon, though some methods may be easier on your digestive system and lead to better performance than others. Since registered dietitians are the food and nutrition experts, we’ve grabbed a few of their best tips (from those who have run marathons or worked with endurance athletes) for marathon fueling to assist you in mastering your nutrition plan.

Marathon Fueling Basics

First and foremost, know that personalization is key when it comes to a marathon nutrition plan. Each athlete may prefer or require different foods, drinks and/or engineered sports products. The most important part of what you choose is making sure it works for you. Practicing your fueling technique before the race is paramount for optimal performance and for developing a unique plan you can depend on for race day. The standard advice of not trying anything new on race day holds true.

Practicing what to eat is important, but also practicing when to eat as well as other logistics is critical. “If an athlete is stopping to refuel verses eating and drinking on the run, that can make a difference in their food and beverage choices as well,” registered dietitian Amanda Joyce says. Furthermore, being open to different brands and products (or using more than one) may offer more flexibility for some.

Pre-Race Fueling

Like your nutrition plan during the race, don’t try anything new for breakfast on race day!

Depending on what time the race starts, you’ll want to allow yourself enough time in the morning to get up, eat, and digest. Make sure to also drink enough water to ensure you start the race hydrated. The focus before the race should predominantly be on carbohydrates, as they are the body’s quickest and main source of energy. The general recommendation before exercise is to aim for a maximum of 1 gram of carbohydrate per kilogram of body weight times the number of hours before exercise. For example, a 75kg person (165 pounds) would want a maximum of 150 grams of carbohydrates two hours before exercise.

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Depending on when you eat your breakfast, you may want to add in a smaller snack about 30 to 60 minutes before the race. Half of an English muffin or a piece of toast, a banana, or a sports gel are all great options. Aim for something low in fiber to minimize gastrointestinal distress. Hydrating with sports beverages can help top off glycogen (stored carbohydrate) stores while providing hydration and electrolytes, as well.

Marathon Nutrition During The Race

You should have your fueling strategy planned out before the race and have a general idea of when you plan to take what. Most races will have a specific brand of nutrition supplements for the course. If you’re someone who doesn’t like to carry extra things, train with what will be served on the course so you don’t have to carry it during the race. If what’s offered doesn’t work for you, make sure you practice your long runs with other options.

While athletes have many nutrition choices these days (gels, chews, waffles, blocks), make sure to check the nutrition content ahead of time. You should aim for 30 to 60 grams of carbohydrates per hour. Dietitian Lynn Grieger offers these words of caution: “Most runners think that electrolyte beverages also contain carbohydrates—some do, but most don’t. Make sure you’re also adding in carbohydrates in one form or another.”

Water is important, but relying on water alone without a balance of carbohydrates and electrolytes can result in overhydration and decreased performance. Grieger, who has run over 50 marathons, drinks 4 ounces of Gatorade that she carries herself every 15 to 20 minutes and uses a gel every hour that she washes down with water. If you’re a salty sweater, you can also add in salt tabs throughout the race.

“Many of my clients prefer to carry their own liquids and electrolytes in powder form, such as Infinit or Skratch Labs, that can be mixed with water and gels,” says sports dietitian Angie Asche. “Sometimes they plan to have a friend or family member waiting for them at certain mile markers to hand them their drinks.”

No matter how you orchestrate it, finding a consistent schedule of fueling can be helpful, as it delivers consistent carbohydrates to your working muscles and brain. “I found that taking in 30 grams of carbs every 45 to 60 minutes worked really well for me,” says registered dietitian Megan Robinson, who used Clif Shot Bloks for her marathon. “In warmer temperatures, I used the higher sodium Bloks with extra water, and it helped to keep me hydrated and prevent bonking.”

Personally, I survived my two marathons on gels, Shot Bloks, and dried fruits. I’d rotate between them to prevent any taste fatigue, taking them every 3 to 5 miles, and as needed in the final miles. I also stopped at every water station to make sure I stayed hydrated.

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Some athletes prefer real food over engineered gels and chews. Dietitians encourage practicing often with this approach, as it may be difficult to chew and swallow initially without stopping to walk. Pamela Kikosewin-Holden fuels with dates and a homemade sports beverage (coconut water, lemon juice, maple syrup), replenishing every 4 to 5 miles. Dried fruits, energy bites and salty pretzels are other common “real food” options. Another reason for practicing your nutrition plan is to help train your gut. Sports dietitian Kelly Jones counsels her clients that prefer food to add ginger to energy bites and balls, to help calm the gut and steady performance.

Be sure to pack ample nutrition for the race and make sure to save some for the later miles, when your muscles are more fatigued. A lack of carbohydrates will cause you to “hit the wall,” so some runners like to save more of their nutrition for later in the race. There’s no right or wrong way to do it—just practice beforehand. Remember, it’s better to have extra fuel on hand than not enough.

Refuel Post-Race

After the race, aim for a mix of both carbohydrates and protein within 30 to 60 minutes. Fruit is an easy go-to because it contains quick-acting carbohydrates and is readily available at nearly all races. Higher-potassium fruits, like bananas, raisins, mangos, or oranges, can help replenish electrolytes, as well. Most races will offer sports beverages after the race. Other quick snack options include chocolate milk, a fruit smoothie made with milk or yogurt or a PB&J sandwich. Make sure to follow your snack with a balanced meal.

Dietitians usually recommend a 3:1 to 4:1 ratio of carbohydrates to protein in your next meal. Both are important, as the post-race meal will help replenish glycogen stores, prevent further muscle breakdown, and help rebuild and repair muscle and balance electrolyte status.

As you can see, there are many options available for your race day nutrition, and the best one is the one that works for you. If you’re looking to run your first marathon this year, don’t underestimate the power of a good nutrition plan.

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