For many runners the marathon is the toughest test in running. It’s the combination of distance and intensity that makes it so challenging. There are longer events and there are faster events. But the marathon seems to be almost scientifically designed to push most people just past their limits. You need every bit of help you can get, so the right marathon nutrition approach is critical.

Modern Marathon Nutrition Is Well Understood

For most runners, the 26.2 miles marathon distance is long enough to mean that your body will have exhausted its stores of its preferred energy source for aerobic exercise: muscle glycogen. Most people have around 2500 calories of readily available glycogen stores. The rate at which runners burn glycogen varies. It is linked to the intensity of exercise and to training adaptations that can encourage more efficient use of carbohydrate and fat energy sources.

These challenges explain why most people have heard (or even experienced) about “hitting the wall” or “bonking”. These terms refer to the point when your preferred energy supplies are running out and your body has to switch to favour other sources. As a brief aside, this switch doesn’t take place at a sharp dividing line. There is a more gradual transition between sources. Your body will attempt to optimise its use of the available fuels. Hitting the wall is really the point at which this transition becomes too much to cope with and you feel that you need to slow down significantly. A key point is that you haven’t run out of fuel altogether. You have loads of stored energy as fat. But your body is designed to work most efficiently when using muscle glycogen during aerobic exercise.

The good news is that hitting the wall is not an inevitability. As our understanding of nutrition and training has improved, it’s become possible for most runners to get through a marathon without bonking. This is great news, because it means that more people can achieve their goals.

The following tips are based on practical experience and supported by scientific research. If you follow this approach it will give the best possible chance to achieve peak performance on race day.

During Training

Endurance training puts a lot of stress on your body. Your diet is an important part of making sure that you can train to your best level, maintain energy levels for daily life and minimise risk of injury.

The key is to follow a balanced and varied diet and make minor optimisations to achieve specific training objectives.

Try to focus on eating minimally processed foods as much as possible. The main reason for recommending this is that it allows you to control what you are consuming.

Favour fruit, vegetables, nuts, seeds and whole grains wherever possible. Note that you aren’t limited to “fresh” fruit and vegetables. Dried, canned, and frozen fruit & veg all have their place in your diet. There’s relatively little difference in nutritional value, but the increased convenience and reduced cost generally makes it easier for most people to include more fruit & veg in their daily diet.

Aim to eat around 1-2g of protein per kg of body weight each day. This will ensure that your body has plenty of protein available to help your muscles recover from the pounding during training.

Aim to keep your fat intake to around 1g per kg of body weight. Recently research has suggested that the long-standing prohibition against saturated fat is misguided. That said, fat sources like olive oil, coconut oil, nuts & seeds, and oily fish like mackerel are still good, because they tend to come as part of more nutritionally dense meals.

The main reason for controlling fat intake at this level is to help with weight management. Fats are more energy dense than other foods. If you’re not careful a diet too high in fat may lead to weight gain. Note that you shouldn’t try to reduce fat intake too dramatically, because your body needs fats to function properly.

You should generally look to make up the rest of your daily diet from carbohydrate. Typically, this means eating 4-6g of carbohydrate per kg of body weight per day.

If you follow these basic guidelines for protein, fat and carbohydrate, you’ll end up with a diet where the calorie breakdown is approximately 55% carbohydrate, 25% fat, 20% protein. Personally, I find that thinking in terms of grams is actually an easier way to control my diet than trying to do percentages of calorie intake.

For general training and day-to-day diet management, this dietary approach is largely sufficient. It’s going to ensure you have a good store of muscle glycogen to fuel training. It will mean you have all the necessary nutrients available to support your recovery and health.

Marathon training also includes bigger, harder workouts though. These are where small tweaks can really enhance your diet. These tweaks aren’t really complicated. They essentially involve optimising the timing and composition of key meals.

For training sessions that last longer than 90 minutes, you’ll likely benefit by increasing your carbohydrate intake before and after the training session.

On the day of training and for the next 24 hours, aim to increase your carbohydrate intake to about 6-8g per kg body weight. If you are training at a really high level of intensity within a bigger programme, eg if you’re doing more than 70 miles a week, you may need to go as high as 10g carbohydrate per kg body weight.

For these bigger training sessions remember that it takes around 4 hours to digest most meals, so you want to have a meal that contains 1-2g carbohydrate per kg body weight about 4 hours before your session starts. Focus on simpler carbohydrates in these meals. Think white rice, bread, pasta, potatoes, cous cous, etc.

Experiment with the composition of your pre-training meal to find what is comfortable for you when running. For example, I find that meals with a lot of cheese can leave me feeling uncomfortable when running, so I avoid this on big training days.

As soon as possible after training try to get 1g of carbohydrate per kg body weight and include some protein in a ratio of 4:1 carbohydrate to protein. Milkshakes are a great way to do this. Specialised sports nutrition products are also available and may be more convenient, especially if your training finishes away from home. Sports specific products are also formulated to maximise absorption of key nutrients and avoid digestive discomfort.

The only other thing to add to your diet is vitamin C supplementation. Research studies have shown that endurance training can suppress your immune system and the this can be mitigated by taking additional vitamin C. A dose of between 500-1000mg per day would be normal, although you should always consider checking with the doctor before taking any additional supplements.

One other thing to consider during training is to remember the golden rule of race day nutrition: never try anything on race day that you haven’t practised in training. Ideally, practise your race day nutrition about 4-6 weeks out. This gives you time to try something else if you have any problems.

Pre Race Day

Mention marathon meals to most people and thoughts usually turn to carb loading and eating plates piled with pasta, rice, bread or potatoes. There is a place for carb loading, but it’s definitely not just a case of stuffing your face with a mountain of pasta the night before the race.

Carb loading is definitely effective in ensuring your body is brimming with fuel for race day. To fuel effectively, follow the outline below.

In the 2 or 3 days leading up to race day, adjust your diet to get between 8g and 10g of carbohydrate per kg of body weight. For these few days, favour simple refined carbohydrates and reduce your intake of wholegrains and fibre. You may want to slightly reduce your intake of protein and fat to about 1g and 0.7g per my body weight respectively. Although you may also find this quite difficult to do.

Consuming this amount of carbohydrate means a lot of plain rice, pasta, bread or cereals. It can be very difficult to eat enough just through “normal” foods. This is where energy drinks and bars can help you to boost your carb intake in a more palatable way without adding lots of extra fat or protein calories too. Try to space out your intake rather than focusing on one or two really big meals. Frankly this is more of an issue of digestive comfort than anything else.

In the past carb loading was preceded by a phase of carb fasting. There’s not really conclusive support for whether this is beneficial. It’s probably down to personal experimentation. It’s definitely easier to maintain a healthy balanced diet and then just add some extra carbs nearer to race day.

Race Day Preparation

Ideally your pre-race breakfast should be 3-4 hours before race start. You are aiming for 1-2g of carbs per my body weight. You don’t really want any more than this, otherwise you risk feeling a bit bloated and heavy during the race. Your meal should be high in simple carbohydrates and low in fat and fibre. My personal favourite is a bagel or toast with Marmite, a banana and a glass of fruit juice or a sports drink.

If you can’t eat that early, then it may be better to drink an energy drink or even have a couple of energy gels. If you’re eating / drinking around an hour to 30 mins before race start, limit carb intake to around 60g. Interestingly, this seems to be relatively independent of body mass.

After breakfast you should drink fluids reasonably normally, but think about stopping drinking about 90 minutes to 2 hours before race start to give time to clear your system. The last thing you need is the stress of standing in a huge queue for the loos just before the race is due to start.

Caffeine is a proven ergogenic aid that both delays the onset and reduces the feelings of fatigue. Unless you have a specific condition, you may benefit from a drink containing 100-150mg of caffeine taken between 30 mins to 2 hours before race start. As a guide a typical homemade cup of coffee has about 150mg of caffeine. My approach on race day is to have a cup of coffee with breakfast and then top up with an electrolyte drink containing caffeine about 30 minutes before each start. I like SiS GO Hydro with caffeine, which has 50mg caffeine per tablet. Definitely experiment with caffeine in training. Too much caffeine can increase the risk of muscle cramp.

Even if you don’t want to use caffeine, 500ml of electrolyte drink taken about 30 minutes before race start will ensure you start hydrated and should be about the right time to avoid any additional toilet breaks.

During The Race

In my opinion, the best option for marathon race fuelling is to use gels. Bars are generally too hard to eat while running and take longer to digest. Chews / chomps are a bit fiddly. Energy drinks mean carrying a lot of extra weight.

At most marathon races there may be a few gels available, but probably not enough for optimal nutrition. Ideally you want to take 60g of carbohydrates per hour. This should be a glucose source. This usually means 3 gels per hour. As always, this should be based on practice during training.

Recent research into carbohydrate absorption during endurance activities has suggested that if you use multiple types of carbohydrate, eg glucose and fructose, then it is possible to take on up to 90g carbohydrates per hour. For a marathon this is probably unnecessary. It’s more relevant to ultramarathons. For a marathon the practicality of carrying extra gels, and the risk of gastrointestinal distress mean it’s not really worth the extra few carbs.

Depending on the spacing of drinks stations, you may be better off using a gel that is isotonic, because you don’t need to dilute these with fluid.

Another consideration is caffeinated gels. It can be beneficial to take between 30-50mg of caffeine per hour. This keeps your caffeine level topped up. Typically this means one caffeinated gel per hour. As above, make sure you’ve practised with caffeine in training. You should also avoid too much caffeine. If you’ve taken 150mg before the race, you should be limiting intake to around 150mg max during the race.

My own personal adaptation of this is to start taking gels at about 8 miles and then to take one every 20 minutes. Every third gel is caffeinated up to a maximum of 3 caffeinated gels. This gives me a reasonable balance between staving off the bonk and carrying lots of extra stuff on race day.

Drink according to thirst and personal preference. I like to take a little drink regularly rather than big glugs intermittently. Depending on the set-up at the race this can mean drinking at every station. But for a well supplied race like the London Marathon, you wouldn’t do this, because they have stations every mile. One reason I do this is there is always the risk that you drop a drink or simply miss a station, especially at busier events. Aiming to drink at most stations means I’m not so badly affected if this does happen.

After The Race

Well done! Finishing a marathon is absolutely worth celebrating. Before you tuck into a well-earned plate or two of scoff (and maybe a little drinkie), see if you can get some good quality recovery nutrition inside you.

There’s some reasonable science to say that you’ll recover best if you consume food with a 4:1 ratio of carbohydrate to protein within 20-30 minutes of finishing a hard exercise session. A chocolate milkshake will get pretty close to this magic ratio. But it might not be easy to get hold of one or it might not keep well in your race bag. You can get some convenient alternatives in recovery bars or drinks.

If you don’t have a specific recovery drink, your race bag will probably have some goodies in it. Try to go for the thing that is high in carbohydrate and low in fat first. Malt loaf or a sports snack bar will be good options. If there’s a chocolate bar, leave that until a bit later, if you can. Honestly, your body will thank you for the abstinence the next morning.

How much do you need to eat for recovery? For a marathon, a good guide is to get 1g of carbohydrate per kg body weight in the first 30 minutes and to judge protein intake to match the 4:1 ratio.

Since you should be resting for at least a few days after a marathon, it’s actually not crucial to be too restrictive in recovery food. Assuming you manage to take on something suitable early, you can eat a normal diet, or, frankly, an abnormal celebratory diet, for the rest of the day. Aim to keep a reasonable level of carbohydrate intake, but if you aren’t due to do a heavy training session for at least a few days, that will be plenty of time to replenish your glycogen stores.

And that’s about it. All that’s left is to enjoy your achievement. And start planning your next one.

Get Involved

Please can you add any ideas, experiences or comments on this advice?

• What does your diet look like during training?
• How do you fuel during a marathon?
• What’s the treat that you keep thinking about to motivate you to cross the line?

References & Credits

Photo Credits

• “Run” by Dominik Golenla [CC BY-ND 2.0] via Flickr
• “DSC_0008 by Song River – CowGirlZen Photography [CC BY 2.0] via Flickr
• Thomas Rehehauser via unsplash.com
• “k7659-1” by U.S. Deparment of Agriculture [CC BY 2.0] via Flickr
• “Everybody Has To Go – Starting Line – 2011 Eugene Marathon” by Michael (a.k.a. moik) McCullough [CC BY 2.0] via Flickr
• Lotte Löhr via unsplash.com