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Top tips on how to fuel your run

April 06 2022 6 min read

Have you been inspired by the 40,000 runners that took part in the sweltering heat of the London Marathon last weekend? We most definitely have! Whether you’re training for your first 5k run or your next marathon, knowing what to eat and when can be a little confusing. Just as important as the hours you train for, is what you eat to nourish and fuel your body. So, The Food Doctor has put together their top tips to help you along the way and get the most out of your running.


During exercise, and especially at high temperatures, your body loses water and electrolytes (.i.e. sodium and potassium) through sweat. Your heart finds it harder to pump blood around your body when you’re dehydrated and this can leave you feeling lethargic, dizzy and nauseous.

Before you start your run make sure you’re hydrated by drinking around 500ml of fluid a few hours before and topping it up just before you start. If your urine is a pale yellow colour then you’re hydrated. If your run last less than 60 minutes then you don’t need to carry water with you and you can rehydrate when you finish. If you’re running for longer or in a hot climate, then you may want to take a water bottle with you and sip on it.

Water will rehydrate you during shorter runs but for longer runs you may need electrolytes and sugar. Sports drink are handy but they’re often expensive and packed full of sugar and preservatives. You can create your own rehydration drink using water, a squeeze of juice and a pinch of salt. Coconut water is great for longer runs as it naturally contains electrolytes and sugar. Caffeine before a run also helps to give you an extra boost of energy. After your run drink around 500ml of fluid in the first 30 minutes and make sure you continue to sip on water over the next couple of hours.


When it comes to exercise, protein is one of the most important nutrients post-exercise to help your muscles grow and recover. Protein can’t be stored in the body and you can only absorb around 30g in one sitting, so you need to be eating protein throughout the day, rather than all in one go.

Proteins are made up of building blocks called amino acids and our bodies need a steady supply of these amino acids to perform at their best. Foods like meat, fish, eggs, dairy, quinoa, soya beans and buckwheat are considered ‘complete’ proteins as they provide the body with all the essential amino acids, whereas certain grains, legumes and nuts lack an amino acid and are considered ‘incomplete’ proteins. Read our article on protein to find out how you can combine foods to create ‘complete’ proteins.


Whilst endurance athletes can teach their bodies to oxidise fat more efficiently as fuel, carbohydrates are the most readily available form of energy for the body. The type of carbohydrates you should eat will depend on when you want to eat it them.

Simple carbohydrates or high GI foods like dried fruit and bananas are broken down rapidly into sugar and provide the body with a quick burst of energy, great just before a run or during a long run. Whereas complex carbohydrates or low GI foods like wholegrains, sweet potatoes and legumes are broken down more slowly and provide the body with a slow realise of energy, ideally eaten 3-4 hours before a run to avoid digestive problems.


We all know fruit and veg are good for us but they’re even more important when you’re putting your body under stress. Although exercise is incredibly good for your body, it produces free radicals, which are molecules that contain oxygen atoms that attack our cells. Our bodies produce plenty of antioxidant enzymes to deal with these free radicals but to support this process we should be eating lots of antioxidant rich foods like colourful fruit and vegetables.
Make sure you are eating lots of different veg with every meal and try not to have the same ones every day. Smoothies are a convenient way to eat lots of fruit and veg, especially when you’re on the move and they keep in the fridge for a few days.


To get the most out of your training, it’s important that you’re aware of when’s best to fuel your body.

If you’re running first thing in the morning then you may not want to eat a big breakfast. Choose something small like a banana or a small smoothie to eat 30 minutes before as it will digest very quickly and won’t sit on your stomach.

Some people like to exercise on an empty stomach as they believe it burns more body fat. However, although exercising fasted can be beneficial for training your body to burn fat more efficiently and for blood sugar control, if you’re exercising for long periods of time then your body may not have enough energy and you won’t perform at your best. If you’re going to eat breakfast a few hours before your run, then oats like porridge with berries and nuts are a great breakfast as they slowly realise their energy, or wholemeal bread with poached eggs, tomatoes and spinach.

If you’ve eaten a large meal that contains protein, fibre and fats, then you should leave around 3-4 hours before your run to give your stomach enough time to digest the food. If you’re going for a run after work and you haven’t eaten anything since lunch, then you may want to have small snack mid-afternoon which contains some protein and carbohydrates like houmous and pitta bread or crudités, a fruit and nut bar, nut butter on toast, or yogurt and fresh fruit. If you’re eating 30-45 minutes before your run, make sure your snack is low in fat and protein but high in carbohydrates such as a piece of fruit or a handful of dried fruit or granola.

If your run lasts less than an hour then you should have enough energy to keep you going but if you’re running for longer, your body will use up its carbohydrate stores and will start to burn fat as its main energy source. To keep your energy levels topped up you can have a drink or snack that contains easily digestible carbohydrates and very little protein or fats such as a homemade sports drink, dried fruit, bananas and dates. Some runners will choose to eat energy gels, blocks and sweets during a run which can be convenient during a race, but be aware that these foods are highly processed and can be expensive.

What you eat after your run is important especially if you’ve been for a long run, as it will help kick start your muscles growth and repair process. There is a 45 minute window after your run that your muscles are most efficient at absorbing nutrients. Your body finds it easier to absorb protein when carbohydrate is present, so always make sure you’re eating them together. Try to eat a small snack which contains a good amount of protein and carbohydrates within this time period such as peanut butter on wholemeal toast, yogurt and granola. If you’re on the move then homemade smoothies made with a protein like milk, yogurt, nut butter or protein powder are really useful as you can take them with you.

Try to eat your post run meal, which might be breakfast after a morning run or dinner after an evening run, within 2 hours of finishing. This should be a balanced meal of protein, carbohydrates, healthy fats and lots of vegetables like roasted salmon with brown rice or sweet potato wedges, roasted peppers, steamed kale and a yogurt dip.

Happy running.