How To Fuel For The London Marathon

Article by Faye Townsend BSc, ANutr, SENr

With just over 5 weeks to go before the 2022 London Marathon, it’s time to start considering your race day nutrition strategy.


Developing a nutrition plan for the run up to the race, during and afterwards, will help to ensure that you maximise your performance and recovery, as well as your enjoyment of the race. Here are some simple tips to ensure you power through to the finish line.

32-48 hours before

The magic question, should you be carb-loading for the London Marathon? The body has stores of both carbs & fats that can be used as fuel for exercise. Unfortunately, the stores for carbs are much smaller than those of fat and can be depleted after prolonged exercise. To avoid ‘hitting the wall’, you need to keep those carb stores topped up! In order to start a race with optimal glycogen (carbohydrate) stores it is important to eat carbohydrate-rich in the day or days before the race, also known as carb-loading. Alongside this, the amount and the intensity of training needs to be reduced to limit the use of glycogen stores.

One mistake that is often made by athletes is confusing carb-loading with overeating. This increase in carbs should be at the expense of some protein and fat, to avoid any weight gain prior to the event. This performance plate can be a useful guide to based your meal around:

In the 2-3 days prior to the event, aim to focus meals around…

  • Bread / Bagels

  • Pasta

  • Rice

  • Potatoes

  • Cereals 


Try to also add in carb-rich snacks such as fruit, cereal/granola bars, fruit juices etc .

In addition to this, aim to stay well-hydrated. A simple way to assess your hydration levels is looking at the colour of your urine. You should be producing a pale-straw colour, as shown below. A small volume of concentrated, dark urine would indicate that you are dehydrated and need to drink more.

Having said all of this, one of the most important aspects of preparation is “training your race nutrition”. Most people wouldn’t go into a race without training the distances, so you shouldn’t go into a race without training your gut. Race day is not the time to experiment with new foods/products.

The morning of the race:

  • On the morning of the race, this is your chance to top up your glycogen / carbohydrate stores before you get started. Here are my key tips for your race day morning breakfast:

    Aim for low fibre & low-fat options to avoid any gut issues

  • Eat 2-4 hours prior to starting to allow food to digest
    Have a light portion. Most of your carb-load should have been in the 32-48 hours before your event.
    Include foods that you’re familiar with, that sit well with your gut. This should be trialled in training.

  • Drink but not too much. Hydration is a fine balance, you don’t want to start dehydrated nor overly hydrated. After all, unnecessary pitstops will add time!  Try to aim for around 5-10ml of water /kg BW in the 2-4 hours before the race. During the 60 mins before, you may want to sip small amounts to satisfy your thirst.

  • Consider caffeine carefully: Caffeine is a stimulant that may improve performance by reducing your perception of effort. However, it should also be used if you’ve trained with it, as it’s tolerated in different amounts. A general recommendation is 1 – 3 mg/kg body weight, or about 100 – 200mg. You can take it as coffee, gels or pills. Caffeine peaks in your blood stream after about 30-60 mins of ingestion, therefore you may take it shortly before you start or towards the latter stages of the race to give you that final boost.

During the race:

If your goal is to optimise performance during your race, It’s recommended to ingest carbohydrates during prolonged exercise such as during a marathon. As mentioned before, your glycogen tank will get depleted whilst running, so it’s important to keep it topped up.

For exercise lasting 1-2 hours, 30g of carbohydrates per hour is sufficient. With increasing duration, it is recommended to increase the intake up to 60 g/h and beyond 2.5h even up to 90 g/h.

 90g of carbs per hour is a lot to take in, therefore this level may not be practical for everyone. With clients I will start low and gradually build this up throughout training to allow the gut to adapt. This reiterates the importance of trailing out different amounts and types of carbs during training.

What does that look like in terms of food/drinks? Here are a few examples that contain approx 30g. However you can get it from many other food, drinks and sports products (bars, gels, chewables, drinks )

Start fuelling 30-45 minutes into your run and don’t wait until you’re depleted. Depending on pace and what you’ve trailed, you may aim for 15-30g of carbs every 30 minutes, the key is little and often. 

Hydration

As for hydration, your target for fluid intake should ensure that you lose no more than 3% of your body weight. You can work out your sweat race using this equation. You will therefore be consuming fluid at a rate that is just below your sweat rate. Drinking to thirst is generally fine if you are running slower, however at faster paces, you may be best sticking to a pre-planned hydration strategy. As a rough guide, aim to drink 125–250 ml (or an amount tailored to your sweat rate) –about two or three big swigs – every 15 to 20 minutes or according to thirst.

Drinking too much water can dilute the body’s supply of electrolytes, causing electrolyte imbalance (or hyponatremia). If significant fluid replacement becomes necessary due to long bouts of exercise, such as running a marathon, it is important to include electrolytes too, especially potassium and sodium, with your water in order to maintain optimal hydration.

Just like new shoes though, don’t try out new plans for fuel and fluid replacement at a major

Recovery

The period after you finish the race is critical for recovery. If you recover better, then you will be able to train again much quicker. Failure to do so, could leave you feeling sore and fatigued

Whilst this doesn’t have to be straight away (i.e within the so called 30 min anabolic window), it is important to refuel efficiently within a couple of hours.

REFUEL: muscle glycogen (carbohydrate stored in muscle) after training. During the first two hours after exercise, glycogen synthesis (your body’s ability to refuel) is at its peak. Aiming for around 1g carb/ kg in each meal.

REPAIR: muscle tissue and stimulate muscle protein synthesis (growth) with high quality protein. Aim for 0.25-0.4g per kg/BW or 15-40g at each meal/snack over the day. You can get 20g protein from 3 eggs; 500ml milk; 250g Greek yogurt or 25g whey powder.

REHYDRATE: with fluid and electrolytes based on sweat loss in training. Over the following few hours, I’d suggest trying to replace with 1.2 -1.5x the amount of fluid that was lost during the event.

Remember recovery is an all-day process, therefore after your race, regular frequent meals and snacks should be consumed.

Interested in working closely with me to develop your personalised marathon nutrition strategy? I work with clients privately 1-1 at the Rhitrition clinic, enquire here.


This blog was written by Faye Townsend who is a Registered Associate Nutritionist (ANutr) and Sports Nutritionist (SENr). Faye has achieved a first-class bachelor (BSc) degree in Nutrition with Food Consumer Science and a Postgraduate degree in Sports and Exercise Nutrition. Specialising in Sports Nutrition, Faye’s mission is to fight modern day dietary and fitness myths and help people find an approach that works with their body rather than against it. She shares evidence-based content for all things nutrition and exercise on her Instagram @faye.nutrition.

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