A Complete Guide to Proper Marathon Nutrition

Training for your marathon means more than just putting in miles. Having your nutrition plan dialled in for before, during, and after the race is equally important. This guide will help you create the right plan for all aspects of your race-day nutrition.

How do I fuel for a marathon?

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  • Test a variety of food options in your training to determine which ones work best for you.
  • Understand what will be provided in aid stations.
  • Increase your carbohydrate intake moderately in the days before your race to fill up your glycogen stores.
  • Eat a familiar breakfast 3-4 hours before your start. Avoid excessive fibre, fat or protein.
  • Bring a gel or carbohydrate drink to sip an hour before your start.
  • Focus on hydration and carbohydrate intake during your race.
Glucose is the main source of fuel for our cells. When the body doesn’t need to use glucose for energy, it stores it in the liver and muscles. This stored form of glucose is made up of many connected glucose molecules and is called glycogen


Nutrition continues to be a much-discussed topic amongst marathon runners. Questions about what to eat before, during, and after the race are commonly asked by beginners and even advanced runners. Here is a quick guide to getting your nutrition for your marathon just right.

Interestingly, the story does not start the week before the race, like training it starts many weeks before the event! After a race, it also seems to be one of the main topics, especially for runners who did not achieve their goals or had problems along the way.

Training and nutrition are the two of the most important factors determining performance on race day. Most runners spend many hours per week training, planning, and preparing their training sessions… but how much time is spent on nutrition? Often, nutrition is taken for granted and this could jeopardize all the hours and days of hard training.

The Early Preparation

Preparation starts many weeks before the event. You need to know some of the basics of the race like what nutrition will be provided on the course, where are the feed stations, and what are the weather conditions likely to be. You may not be able to influence the weather, but you can prepare for the conditions. 

Finding out what nutrition is going to be handed out is important too because it would be a good idea to practice with this nutrition and make sure you can tolerate it and you can adapt to it. If you can’t tolerate it, it is better to find out weeks in advance than on race day.

Train Your Race Plan

The first step is to figure out what nutrition works best for you. This includes not only products but timing as well. Start doing this 10 weeks before the event, pick your long-run training to practice and follow your plan, or build up to it. 

As mentioned above, first try using the products that will be available on the course. If those do not agree with you, start experimenting with other products.


In the days before the race, you should make sure your fuel stores (muscle glycogen) are full. In the old days, extreme carbo-loading regimes were followed with days of no carbohydrates, days of extreme carbohydrates, a depletion run a week before, etc. This practice is not necessary. Very high muscle glycogen levels can be achieved by just eating more carbohydrates.

Eating more carbohydrates does not mean overeating or eating as much as possible! It just means making sure more of your daily calories are coming from carbohydrates at the cost of some fat. 

It is a good idea to have the last large meal at lunchtime the day before and to have a lighter meal in the evening. This is also something you should practice in the weeks before or when you have a smaller race coming up. 

If you frequently suffer from gastrointestinal problems, reduce your fibre intake to a minimum the day before the race.

From a purely practical point of view, you also need to plan in advance, especially if you are travelling. Make a reservation at a place where you know the food is good. Don’t wait and make it up on the go and end up at a fast food place or lining up for hours. Your legs need to work hard enough the next day.

Pre-Race Breakfast

Breakfast is important because it replenishes your liver glycogen. Carbohydrate is stored in the liver but during the night the brain uses these carbohydrates so when you wake up there is not much left. 

Since this will delay the point at which you bonk, Stop laughing and read on – (Bonk definition and meaning – It’s a total inability to continue, marked by nausea, extreme physical weakness, poor coordination, and a profoundly awful feeling. Essentially, bonking is exercise-induced hypoglycaemia or low blood sugar)it is important to eat a carbohydrate-rich breakfast. Again if you suffer from gastro-intestinal problems, reduce your fibre intake

Exactly what the breakfast should consist of depends on personal preferences. Some people run really well on a couple of bagels and a coffee, others prefer oatmeal, waffles with syrup, a couple of energy bars or a small bowl of rice. Whatever you select, I would recommend that it has at least 100 grams of carbohydrates and that you use this breakfast at exactly the same time before hard training and smaller races.

The best timing is probably 3 to 4 hours before the start. If you don’t suffer from gastrointestinal distress 2 to 3 hours before might still work.

Check your urine colour. If it is pretty light you are ok, if it is dark, (Dark urine is most commonly due to dehydration) keep drinking a little more. No need to go crazy on the fluids but you don’t want to start with dark-coloured urine.

The Hour Before the Start

Make sure you bring a water bottle to sip and a gel to take in the 15 minutes before the race starts. Practice this several times in training. Whatever you consume in the minutes before the start will become available during the run because it takes a little time to absorb. I therefore usually calculate anything you take in this timeframe as part of your carbohydrate intake during the race.

During the Race

The main rule of thumb for mid-run food is to find something that will give you energy and is easy to digest, and kid-sized candy is actually something that many runners stick in their pockets before heading out the door. As a rule, the body needs fast-absorbing carbohydrates that will boost blood glucose levels and send sugars through the bloodstream and into the muscles.

It doesn’t have to be a candy bar, though. Most runners get their quick-digesting carbs from gel packets or sports chews, which are easy to slurp down while running. Other examples of easy-to-eat simple sugars include sports beans, fruit drops, and even thin, cookie-like waffles. 

You can also get sugars from a sports drink, like Gatorade or Maurten, a drink mix that’s an alternative to mainstream sports drinks and that’s used by many elite runners.

“I think GU and gels are getting knocked since they are processed sugar,” explains Kelly Hogan, M.S., R.D., who works with athletes and has run 11 marathons herself.    “But it’s only sugar for a reason—we need it for running.”

That said, not everyone can tolerate the same types of foods. “It’s important to test different foods to see what your body can handle,” Hogan reiterates. If highly processed foods aren’t your thing, she recommends trying a less processed option, like dried fruit or pretzels. 

For coffee lovers, there are caffeinated fuel options! Certain energy gels also include caffeine; the amount typically ranges from 20 to 40 milligrams, though some are packed with up to 150 mg. 

While caffeine can give runners a nice jolt of energy, it isn’t a necessary additive to your fuelling regimen. “Caffeine intake during the run is meant to give a bit of an energy boost, but is different in how it affects various individuals,” Hogan explains.

“Starting out at the lower end of caffeine—that’s 20 to 30 mg—is a good idea to see how the body reacts, as opposed to going for a gel with 75 to 100 mg of caffeine right at the start.” Hogan also suggests alternating between non-caffeinated and caffeinated gels just to stay on the safe side. 

Unlike sugar in gels, caffeine stays in our system longer. “We don’t want to be up all night after a long run or race, or have lingering feelings of the jitters, nerves, or anxiety.”

What should I avoid? 

“Save the protein for after the race,” advises Hogan. “Calories from protein and fat won’t do much for your body. Fat especially can be the culprit of GI issues since we digest it the slowest.” Fibre could cause tummy trouble, too, since it also takes a toll on our digestive system.

For this reason, avoid foods like leafy greens, cruciferous vegetables (like broccoli and cabbage), and beans, along with red meats, fish, and cheese 12 hours before a long run or your race. Aim to have your pre-race meal be about 75 per cent carbohydrates, and stick to mainly carb consumption when you’re out on the course.

When should I eat? And also, how much should I eat?

“The general idea is to start with consuming 30 to 60 grams of carbohydrates per hour,” says Hogan, which is the range our bodies can absorb glucose and varies slightly depending on how big you are, how fast you’re running, and how quickly you’re burning through your calories. 

This amount of carbs per hour could include two 1-ounce bags of sports beans or two energy gels. “For most people, start to fuel 30 to 45 minutes into the run to get a head start on your glycogen storage.”

If two gels seem too hard to stomach, go for a combo: a mixture of chews, beans, or a gel will also do the trick. Keep in mind that sports drinks, though they’re liquid, provide carbs, so you should factor that in when calculating your carb intake.

What’s the deal with water? 

Hydration is another critical component of your fuelling strategy.  Douglas Casa, PhD, professor of kinesiology at the University of Connecticut who has worked with athletes for years and is an avid trail runner, recommends carrying water with you—whether in a hydration pack, fuel belt, or handheld water bottle—so you can sip water throughout your run versus relying on aid stations, where people tend to gather to drink down fluids.

“This allows you to drink whenever you want and you avoid the rush of people at the aid stations,” he explains. 

Just like calorie consumption, there isn’t a one-size-fits-all amount when it comes to hydration. In general, your fluid intake should depend on your sweat rate, which is the amount of fluid you’re losing through sweat while exerting energy. Sweat rates vary depending on body size, activity intensity, and environmental conditions. 

Hyponatremia is a rare and dangerous medical condition that occurs when the concentration of sodium in your blood is abnormally low, which can happen if you drink too much water. 

While Hogan notes that hyponatremia is rare, it’s important to understand the warning signs. When you’re drinking, make sure your body feels satisfied but not overly full. If you feel extra bloated and start to become dizzy and disoriented, you must get medical attention. 

Casa echoes this sentiment; if you’re aiming for a five-hour finish time and the race conditions are mild, it’s easy to overcompensate and think you need to be drinking loads more. 

Figuring out your sweat rate will give you peace of mind and more confidence when you toe the line, because of course, you still do need to hydrate adequately throughout the race to avoid dehydration, another dangerous (and more common) condition.

Electrolytes are minerals that keep our systems functioning and, in the case of extensive sweat loss, will need to be replenished. It’s easy to add electrolytes—especially sodium—into your running diet; sipping on Gatorade, using Nuun tablets, or even munching on some pretzels will help restore the electrolytes that become depleted in the body.

Nuun Tablets are portable effervescent hydration tablets/capsules to replace essential electrolytes whilst training and racing,

“Sodium is extremely helpful in a beverage,” notes Casa. “It keeps the thirst mechanism on longer so you replace the fluids you need, conserve urine, and replenish the sodium you’re losing in sweat.” 

After the Marathon

Although there are guidelines to recover quickly after a marathon. Does it really matter that much? Most people won’t run another marathon the next day or race again for a couple of weeks. So enjoy your achievement and indulge in moderation!


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