When it comes to preparing for a marathon, your training is not just physical, it’s also nutritional. 

By Joanna Burchartz

BSc(Hons) Nutrition & Food Science 

The Beachy Head Marathon

The month of October brings us autumn leaves, darker evenings, trick or treat and down here in Eastbourne, the Beachy Head Marathon! Originally the Seven Sisters Marathon, this event first began in 1981 with less than 300 walkers and runners. Over the years it has evolved and grown to become one of the biggest off-road marathons in the UK, with a demanding route taking you through the beautiful countryside of the South Downs National Park and along the stunning East Sussex coastline. 

This year’s event takes place on Saturday 26th October and as runners prepare for the big day with training and practice runs, it is just as important that they take the time to consider their diet and prepare themselves nutritionally for the big race. Planning ahead and eating right is a very important factor in achieving your best performance and optimum comfort during and after your marathon run. 

Why is nutritional training important?

Let’s try and keep this simple – as with any exercise when long-distance running your body needs energy. The most efficient source of energy comes from carbohydrates in the diet which are stored as glycogen in the muscles and liver. However, there is a limit to how much glycogen can be stored in the body, generally around 1,800 to 2,000 calories. Of course, everyone runs at a different pace and has a unique body mass, but on average we burn about 100 calories per mile when running a marathon – so if you do the maths, you’ll see that we can’t store enough glycogen to see us through to the end of the run!  

Our backup energy source then is fat, a slower source of energy and we need to train our body to be more efficient at burning fat for energy prior to the big day, something that needs to be incorporated into your pre-race planning. 

What do I need to know about planning my diet for a marathon?

As we’ve said, carbohydrates are the most fuel-efficient nutrient so prior to race day you need to increase your intake to ensure your glycogen stores are at their maximum level – this process is known as carb loading which we’ll talk about in a bit more detail further down. 


What I tell you next is EXTREMELY important when planning your eating regime before and during your marathon run. You MUST know which foods work best for you and which could cause you problems. So, try out different diet routines prior to race day. Experiment with different meals the night before a training session, try out your breakfast plan before a long practice ran, sample some mid-run snacks and drinks. Everyone is different so you need to know what works best for you – planning ahead means you’ll find the best foods so that you can be at peak performance and have no digestive issues during your marathon. 

What does it mean to ‘hit the wall’ and how can I avoid it?

You may have heard the term ‘hit the wall’ being used in relation to endurance sports such as long-distance cycling and running but unless you’ve experienced this you may not know quite what it is… Basically this is the point at which your glycogen stores have been used up and your body now needs to rely on fat as your energy source. I’m told that when you hit the wall your legs become heavy, each step forward is an effort, you’re overcome with exhaustion and your brain is just telling you to give up! 

So, how can we avoid this unpleasant feeling, power through and keep going to the finish line? The key is in the planning and the training, both physical and nutritional. 

Before, during and after the big race

Pre-Marathon Diet

During your pre-marathon preparation, you need to train your body to be more efficient at burning fat for fuel. Work your way up to longer training sessions so that your body will need to start using your fat reserves and try some pre-breakfast runs when your glycogen stores are lower – but take it easy and increase your times gradually. 

About 2 or 3 days before the actual marathon it’s time to start carb loading. This is exactly as it sounds, loading up on carbohydrates as this will be your main source of calories. By this point, you’ll have reduced your training so the carb-loading diet means you’ll achieve maximum glycogen levels by race day. These calories should come from carbohydrate sources such as rice, whole grain pasta, cereals, bread, starchy vegetables, yoghurt and fruit.

During the day before the race, it’s a good idea to graze on high carb, low-fat foods to keep those glycogen levels topped up and then have a healthy meal high in carbohydrates in the evening. Eat something you know you can digest easily and no spicy, high fat or bulky foods – you don’t want any problems the next day.

On the morning of the race you’ll need to top up on those carbs again, so have a good breakfast, high in carbohydrates with some protein and also some fat to help kick start your fat-burning metabolism. Try to avoid having too much fibre right before the race as this can cause digestion issues and the last thing you want is to feel uncomfortable and bloated while running. 

Along with ensuring your glycogen level is at its maximum, you must also be well hydrated prior to the race, so make sure to be drinking sufficient water, little and often during your training and leading up to marathon day – but don’t drink excessive amounts of water as that can lead to other problems.

Topping Up During the Run

The run has started and you’re on your way! But you still need to have a diet plan in place – which you will know by now as it was part of your training. You’ll remember we said that the body can only store around 2,000 calories as glycogen and on average, this means that when you reach the 18-20 mile mark, your reserves will be running low and you really don’t want to hit that wall! So, it is essential to keep your glycogen levels topped up throughout the run. Most marathons provide snacks at the various checkpoints along the route and the Beachy Head Marathon will keep you supplied with things such as bananas, mars bars, jaffa cakes and sausage rolls. You might also want to carry some energy gels with you or if you prefer, a supply of jelly babies. Both will work in the same way as they contain simple carbohydrates (ie. sugar) which are quick and easy to digest and give you the instant energy boost that you need when you’re partway through a marathon run. This should ‘wake you up’, make your mind feel more energised and help you to keep ongoing. 

But remember, you must keep topping up regularly DON’T WAIT till you reach the halfway point, you need to top up little and often throughout the run.  

You need to apply the same method to hydration. DON’T WAIT till you feel thirsty as by that point you’ll already be dehydrated. Drink frequently throughout the run – the checkpoints always have plenty of water and/or juice. However, do keep in mind your checkpoint routine… drinking while running is an art and not everyone is accomplished at it, especially if the water is provided in a cup!! So slow down or walk as you come towards the checkpoint and keep at that pace while you drink to make sure you rehydrate properly then work back up to your regular pace – you’ll benefit in the long run. 

Refuelling After the Run

Woohoo! You made it over the finish line – congratulations!! However, the run may be over but the nutrition plan is not. You need to rehydrate and replace sugars immediately so grab a sports drink or orange juice and get those fluids and sugars back into your system. Then within 20 to 30 minutes, you need to have a good meal – again high in carbohydrates to replace those used during the run with the addition of some protein which will help with muscle repair and recovery and keep drinking plenty of water to get fully rehydrated.  

Prepare for your Marathon Run

So here are the key points to remember about your diet training when preparing for your marathon:

  • Plan ahead – try out foods and snacks during practise runs so you know what will work best for you on the day.
  • Carb load in the 2 or 3 days before the run so you maximise your glycogen stores.
  • Top up regularly on sugary snacks or energy gels during the race to keep up your energy levels.
  • Hydration, hydration, hydration – don’t wait till you’re thirsty.
  • Rehydrate and refuel as soon as possible after the run for maximum recovery.

If you follow these tips you’ll be energised and ready to run your best.

Enjoy and good luck!