How to fuel long runs so you feel good all the way to the end

It’s important to understand how to fuel your long run, so you can make your target distance. Surviving on little to nothing when running for more than an hour is not going to be sustainable or enjoyable.

Our bodies rely on glycogen stores for energy when running. This predominantly comes from carbohydrates, as our bodies turn it into energy faster than other sources, such as fat or protein.

When our bodies’ natural stores get used up to the point of depletion, we feel drained and it’s hard to carry on running. It’s also known as ‘hitting the wall’, but it’s avoidable if you fuel correctly.

Several studies have shown that carbohydrates can enhance performance on a run of more than one and a half hours. This means that if you get your fuelling strategy right, it can make your long run feel much easier, as you’ll have more energy.

With this guide we’ll help you create a plan to fuel your long run so you can boost your running performance and finish your target distance.

How important is it to have the right fuel when running?

If you don’t have the right fuel, your body will struggle with the demand you’re placing on it during a long run, says senior lecturer in Nutritional Physiology at Manchester Metropolitan University, Dr Adora Yau.

“Your body needs an energy source to perform the task. This energy comes from carbohydrates, which are stored as glycogen in our muscles and liver. When these stores are used up, running speed and intensity will decrease.”

Typically, an adult will have 400g (14oz) to 500g (1lb 2oz) of glycogen stores, which sustain one to one-and-a-half hours of running, says Dr Yau.

“But to maximise glycogen stores for an intense, long run, have high carbohydrate meals in the two–three days leading up to your long run.”

This will ensure your stores are topped up to fuel your long run.

Choose your carbohydrates wisely, as some have lots of refined sugar or are ultra- processed. Good options include whole grains such as brown rice, as well as quinoa, sweet potatoes, black beans, and whole wheat pasta.

How does the body use fuel on a long run?

Our bodies are constantly using fat and carbohydrates for fuel and this increases with running, says Yau.

“Endurance running is an aerobic exercise, which means oxygen is used. This oxygen is needed for biochemical reactions that metabolise fat and carbohydrate to enable the resynthesis of energy molecules called adenosine triphosphate (ATP).”

These energy molecules are needed for cellular processes, but particularly muscular contraction during exercise or running, to enable us to move, explains Yau. By ensuring we have carbohydrates in our diet, we can equip our body with energy stores to fuel your long run.

How does caffeine help fuel long runs?

Researchers have been studying the performance enhancing effects of caffeine for more than 100 years. A small study showed exercise capacity and performance improved in older adults after ingesting 3mg per kg of bodyweight of caffeine. The participants also showed ‘readiness to invest effort in activity’ compared to those who were given a placebo.

The evidence suggests using caffeine as an ergogenic aid (to enhance performance) could help fuel your long run.

There are various energy drinks, bars and gels that have a measured amount of caffeine in them.

What should you eat before a long run?

Eating easily digestible carbohydrates will help keep your glycogen stores topped up. Foods including bread, porridge and fruit are good choices to help with this. Some choices could even benefit your recovery before you start:

“Eating a handful of blueberries before going for a run can decrease the amount of oxidative stress you have post-running, which will improve your recovery,” explains Josh Gibbs, a plant-based nutrition researcher from the University of Warwick.

Though you might fancy a slab of chocolate for a sugar hit, it’s not going to give you the right energy for your run. Pick wisely and you’ll get the beneficial effects long after you’ve finished your run. 

Try a bowl of porridge topped with blueberries and honey for a boost of carbs.

How to fuel during a long run

It’s recommended runners consume approximately 60g (2oz) of carbohydrate per hour for optimal performance, says Dr Yau.

“This target intake can be achieved through ingesting different combinations of sports drink, energy gels, bars, chews, sweets or regular foods.”

Some runners may find they are unable to ingest or intake this amount due to gastrointestinal issues, so it might take a bit of trial and error to find what works for you.

When Sir Christopher Ball ran 10 marathons in 10 days, he told Saga Magazine that he enjoyed snacking on raisins, nuts, jelly babies and Marmite sandwiches to keep his energy levels up.

Make sure you bring a variety of things with you when you set off. You might really want a sandwich when you start, but find you need something easier to swallow 10 miles in.

Experiment with different foods and gels, though it might be an idea to stay close to home or plan toilet breaks along the way, just in case something doesn’t agree with you.

There also isn’t a ‘perfect’ amount to eat; it will vary from person to person. It’s a case of finding what works for you.

How to fuel after a long run

Within 30 minutes of finishing your long run, eat a snack or meal containing carbohydrates (to replenish glycogen) and protein for muscle repair, says Dr Yau. Protein for older adults is particularly important to build muscle mass, and you might need more than you realise.

One study showed that older men who upped their protein intake by 0.54g per kg of bodyweight daily saw their muscle mass improved. Further research suggests that all older adults could benefit from eating more high-quality protein daily.

The current international Recommended Dietary Allowance (RDA) for protein is 0.8g per kg of body weight regardless of age. However, the evidence is growing that it may not be enough for adults over 40 – which is the age when muscle mass starts to decline.

Good protein choices include raisins, avocado, beans, eggs and lean meat such as beef and lamb and poultry. Though you may find it hard to stomach anything too much after a run, do try and eat something, as it will aid your recovery.

Dairy products are also a good choice to include after a run, as our bone density declines as we age. Foods high in calcium such as milk and cheese can provide essential nutrients to help our bodies recover after a long run.

I tend to have a banana, chocolate milk and a packet of goji and coconut protein balls after finishing long distances. Then, a couple of hours later, a takeaway curry or pizza when I’ve had a shower and I’m admiring my new medal.

Hydration is also key for long runs

Sip on water throughout your long run to stay hydrated. Don’t get to the point where you’re really thirsty before having a drink, as you’ll already be dehydrated. Make sure you include it in your fuelling strategy.

There are also electrolyte nutrition products that you can add to your water, which will help replace lost minerals (such as zinc) through sweat. I use Tailwind nutrition as I find it easy on my stomach and the flavour isn’t overpowering.

Fuelling long runs can take a bit of planning, and trial and error, before you find what works for you. But, when you get it right, it will be worth it, as you won’t be running on empty.