Consuming food and fluid on a run can be a new experience for many, and may feel slightly uncomfortable to start with. It's vital to trial fuelling strategies during longer training runs as this will help train your gut to digest carbs while on the move.

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Next, discover what to eat before a run, swim and cycle, as well as the best exercise to burn fat, top tips on staying hydrated and how much protein you need to build muscle.

Tying up running trainers

How far or how long can I run without refuelling?

For runs of less than 1 hour

There's no need for you to refuel on the move, as long as you’ve eaten enough to sustain your energy before you set out. If you exercise in the morning, try to eat a balance of protein and carbs for dinner the night before. If you run during the day or in the evening, choose the right snacks to sustain you instead of reaching for carbs during your run.

For lighter, lower-intensity training sessions where the goal is to improve your fitness, there is often no need to take on extra carbs during your run. Your body will have sufficient energy from fat and carb stores.

For harder runs over 1 hour in duration

Consuming small amounts of high-GI carbs may help maintain your performance but remember, this depends on the goal for your training. If you are 'training low' and trying to adapt to using fat as fuel, you should reduce your carb intake during training.

For a race

Carb-rich food and drinks can be important tools for maintaining intensity – the higher the intensity, the more carbs you'll need.

Consuming carbs during a run should be practiced in the final eight weeks of training for an event such as a marathon, in order to ‘train the gut’ and find out what works best for you. Nutrition strategies are very individual and you need to put the time and effort in to determine what works best for you.

Easily absorbed carbs also provide important fuel for the brain, which allows the body to work harder, especially when muscles begin to tire. Interestingly, research has indicated that using a carb-based sports drink as a mouth rinse may help activate the brain, which can be a useful technique later in the race, especially if you struggle to take on fluids.

What are the best foods to eat on a run to avoid feeling full?

Sticking to easily absorbed, high-GI carbs should help avoid discomfort and nausea during a run. Where possible, try to include some carb-electrolyte sports drinks to meet your fuel and fluid needs.

What are alternative options for energy-boosting during a run?

If you already consume caffeine as part of your regular diet, you can use it in addition to carbs to boost energy and decrease your sense of effort. Check out some of the commercially available sports drinks and gels that contain caffeine, and use these later in the race when your energy levels may be waning.

Woman drinking a sports drink

Should I only eat when I feel hungry or should I snack continually during a race?

Don't rely on hunger as a cue to refuel. As a general rule, practice and refine your fuelling during training and find a strategy you're comfortable with. Taking on carbs little and often, for a constant energy supply, is often the most efficient fuelling strategy.

One of the biggest mistakes on race day is trying to take on too much carbohydrate during the race. Aim for 30g of carbs per hour as a starting point and see how you feel – the maximum you’ll require is 60g/hour – but in practice, most athletes don’t require this amount. Build your strategy in training, find what is comfortable for you and then use it with precision on race day.

Carb drinks are typically the most efficient way to meet these targets, whilst also maintaining hydration. Energy gels, chews and bars will also be readily available on race day and are rapidly absorbed. Small pieces of banana, cereal bars and jellied sweets may also help offset fatigue.

The following will provide a reasonable carb boost – see what works best for you and experiment with different quantities during training:

  • 500ml bottle of commercially available sports drink (30g depending on brand)
  • 1½ carbohydrate energy gels (20g – 25g depending on brand)
  • A small handful of jellied sweets (23g carbs)
  • One large banana (24g carbs)
  • One large cereal bar or carb-based energy bar (choose a low-fibre option) – (up to 45g carbs depending on brand)

Now you know what to eat during your run, get the rest of your training nutrition right:

Carb-loading explained
Meal plans for runners
How to stay hydrated
What to eat when running a marathon


This article was last updated on 13 December 2023 by Kerry Torrens.

James Collins is recognised as a leading Performance Nutritionist through his work with Olympic and professional sport. Over the last decade he has worked with Arsenal FC, the England and France national football teams and Team GB. He has a private practice in Harley Street where he sees business executives, performing artists and clients from all walks of life. He is the author of the new book The Energy Plan, which focuses on the key principles of fuelling for fitness.

All health content on bbcgoodfood.com is provided for general information only, and should not be treated as a substitute for the medical advice of your own doctor or any other health care professional. If you have any concerns about your general health, you should contact your local health care provider. See our website terms and conditions for more information.

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