You’re lining up for a marathon soon and wondering how to fuel during a marathon? Whether it’s your first marathon or you’ve already raced a few, it’s crucial to plan your marathon nutrition strategy. You don’t want fueling mistakes to ruin months of marathon training!
One of the biggest challenges in a marathon is that several hours of effort can seriously drain your carbohydrate stores. When glycogen levels drop too much, performance suffers and you risk the infamous marathon wall.
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The marathon wall
Scientists don’t all agree on the true cause of the marathon wall. For some, it’s mainly central fatigue, your nervous system working overtime to maintain balance, known as homeostasis. For others, it’s peripheral fatigue, muscles getting damaged by physiological and chemical reactions.
In reality, both types of fatigue are linked to heavy demands on the body, and to one key issue, not enough fuel. To contract, muscles need ATP (adenosine triphosphate). ATP is produced from fats and carbohydrates. The faster you run, the more carbs you burn, and that’s often what happens early in a marathon. Once your glycogen stores are depleted, you rely more on fat, which is less efficient at race pace, so your speed drops.
So you need to maximize your carbohydrate stores
Carbohydrates are stored as glucose in the blood, as liver glycogen in the liver, and as muscle glycogen in the muscles. These stores are limited, topping out at roughly 2000 to 2200 kcal combined for liver and muscles.
That’s why you should optimize those stores in the days leading up to race day with high-quality carbohydrate loading. In the final days before the race, focus on carbs and easy-to-digest foods.
Eating on marathon morning
On marathon morning, the rule is simple, don’t eat too much. You need enough energy, but not so much that your stomach rebels. Ideally, eat about 3 hours before the start so you have time to digest. Good options include pancakes, a homemade “sports cake”, honey, applesauce, or even a small plate of rice with ham or tuna.
Most importantly, hydrate well, tea, herbal tea, water. Keep a bottle with you and take a few sips regularly, right up until the start line.
Drinking during the marathon
The most important factor is hydration. It matters in any weather, but it becomes critical above 20°C (68°F). Once you feel dehydrated, it’s already too late.
Most marathons have aid stations about every 5 kilometers, or every 2 miles (New York City Marathon). From the very first station, even at 5 km, take 2 to 3 sips of water, including if you’re running under 3 hours. If you’re running over 4 hours, take more like 5 to 6 sips, because the time between aid stations feels much longer when you’re on the course longer.
Water is your best ally in a marathon. An isotonic or sports drink can be a good idea, but in practice it usually means carrying a bottle, which isn’t very convenient. Plus, it adds weight. If you carry 750 ml of sports drink, that’s 750 grams extra on you. Only elite runners under about 2:20 typically get personal bottles at aid stations, which is probably not your situation.
At aid stations, marathons sometimes offer isotonic drinks depending on sponsors. If you want to use it during the race, test it in training first to make sure you tolerate the taste and digestion. In short, check in advance where the marathon aid stations are on the course and what the organization plans to provide.
Eating during the marathon
For marathon fueling, you should think in terms of your expected finish time.
Early in the race, it’s best to choose moderate glycemic index (GI) foods, for example applesauce, fruit purées, or energy bars that are easy to chew. High GI foods can give you a fast boost, but they can also cause a quick drop in blood sugar later. That’s hypoglycemia, the endurance runner’s worst enemy.
In a marathon, how many gels should you take? First, don’t take an energy gel in the first hour. That can spike your blood sugar too early, then set you up for a guaranteed crash later. Also, most runners’ digestive systems can’t handle eight or ten gels.
Fueling for a sub-3 hour marathon
If you’re running under 3 hours, the time between aid stations spaced 5 km apart is usually 15 to 20 minutes. We recommend your first carb intake around km 10 (or 15), then km 20, using something like a purée or applesauce. From km 25 onward, you can switch to energy gels, for example at km 25, 30, and 35.
Make sure you drink water at every aid station, even if it’s only 2 to 3 sips.
Fueling for a 3 to 4 hour marathon
The time between aid stations will be about 20 to 30 minutes. You can start fueling with a purée, applesauce, or energy bar as early as km 10, then again at km 15 and 20. After that, take energy gels at km 25, 30, and 35. Also remember to drink water at each aid station, even if it’s only 4 to 5 sips.
Fueling for a marathon in over 4 hours
If you plan to run your marathon in 4 hours or more, the time between aid stations is usually 30 to 45 minutes. That means if you miss one, you could go 1 to 1.5 hours without fuel or fluids. So don’t miss any water stations, and ideally start eating as early as km 5, with half an applesauce pouch or half an energy bar. Slower-release carbs matter early in the race. Banana pieces can also work, if your marathon provides them at aid stations.
Switch to energy gels later, because at km 25 you typically still have 2 to 3 hours of running left, which is a long time to finish on gels alone. We suggest not moving to gels or sugar cubes until about km 30, realistically at km 30, 35, and possibly 40 (even though that last one is mostly a placebo effect).
Remember to drink water at every aid station, around 5 to 6 sips, or a bit more if it’s very hot. In your gear, you can also pack a small 250 ml soft flask. Fill it at a few stations so you can sip regularly between aid stations.
The “quick” marathon aid station, or maybe not
If you’re chasing a personal best in the marathon, you’ll want to avoid wasting time at aid stations. Anticipate your line, slow down a few meters to grab your cup and take in your fuel. Always respect other runners, and sometimes it’s better to slow slightly than to miss your hydration or nutrition.
Try not to stop completely, so you don’t break your rhythm. At some aid stations, you can walk for a few meters to relax your leg muscles. Same idea, if you start getting cramps, walking briefly at an aid station can help.
Your marathon nutrition strategy is personal
These are the key principles of marathon fueling. It’s up to you to fine-tune your marathon nutrition plan based on your experience. A marathon is also about discovering yourself and what you can handle. After a few marathons, you’ll know what works best for you, but it can take several tries to dial it in.
In any case, get used to testing your fueling strategy in training, especially on long runs. You can also switch brands if a product doesn’t sit well. For example, gel formulas can vary a lot from one manufacturer to another.
In particular, we recommend Näak gels, with SolidCarbs™ technology that delivers a unique texture, a neutral taste, and an optimized carbohydrate mix for better digestive comfort.
Alright, enjoy the build-up and have a great marathon! 😉 The right nutrition strategy, combined with smart training, will help you make it to the finish line and maybe even set a new personal best. At the latest Paris Marathon, runners from 2:29 to 5:15 used the RunMotion Coach mobile app to prepare and get marathon-specific advice, including marathon nutrition.