With so many voices exalting the virtues of spurious 'superfoods' it's difficult to know what will really help spur us onto faster race times, stronger swims or more fruitful workouts. With a raft of experience honing the diets of elite athletes, performance nutritionist James Collins told us what it's really worth paying attention to when it comes to eating for exercise...


1) Flexible fuelling

The body uses different fuels for energy depending on the intensity of your workout.

For low intensity activity (such as walking and jogging), the body burns fat as its main energy source. As the intensity increases the muscles switch to the ‘quick currency’ of carbohydrates to fuel themselves.

Before longer, low intensity training sessions minimising carbs beforehand (called ‘training low’), encourages the body to become more efficient at using fat as fuel. This means a higher protein meal or snack before this kind of activity is a good idea, such as an omelette, smoked salmon & scrambled eggs, or Greek yogurt.

During harder training sessions, the intensity increases and the body uses more carbohydrate as fuel. This means you'll need to eat a carb-based meal before. Good options include oatmeal, a wrap or quinoa salad.

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A woman stretching after a run

2) Training low

Sports nutritionists use the term ‘training low’ a lot, but what does it really mean?

Training low describes exercising when the muscles' glycogen stores (the body's go-to energy source) are reduced, so the muscles must become more efficient at using fat stores as fuel.

The most common way of ‘training low’ is to exercise before breakfast. More recently, research has shown that training after a protein-based (low-carb) breakfast will also produce the same result.

Other ways to ‘train low’ include training twice a day or following a low carbohydrate diet.

It should be noted that ‘training low’ increases the strain on the muscles, which can reduce the training quality of harder sessions and stress the immune system, therefore it should be carefully planned for with appropriate sessions. Consult a fitness professional if you're unsure how to do this safely and always check with your GP if you have any health concerns.

3) Improve performance with caffeine

Coffee fans rejoice! A morning cup of your favourite brew can give your workout a boost; "Research continues to show that caffeine before exercise can improve performance by reducing the perceived exertion," says James, "Everyone has an individual response to caffeine so make sure you experiment with a cup in training before utilising on the day of an event or race."

Fresh cherries on a table

4) Heal & repair with antioxidants

Minimise the impact on your body of hard workouts by eating plenty of foods that contain healing antioxidants. James explains; "Particularly heavy training sessions can cause an increase in Exercise Induced Muscle Damage (EIMD), resulting in subsequent soreness in the days after. A recovery meal or snack containing carbohydrates (to refuel) and protein (to repair) is key to start the recovery process, however antioxidants may be important as they help to scavenge the additional free radicals caused by exercise that can damage cells. Research has shown that cherries, blueberries and pomegranates in particular can have a positive effect, though go easy on high-dose antioxidants (e.g. vitamin C) which may actually hinder the muscle's ability to adapt to training."

5) Just beet it

The fitness world is full of ‘go-faster’ fads that promise to rev your engine and have you flying over the finish line. Beetroot juice is one of the few products with claims that have stood up to rigorous testing; "Recent research has continued to show that dietary nitrates (in particular from beetroot juice) can be an endurance booster," explains James, "They work by improving the efficiency of the muscles as the nitrates reduce the amount of oxygen required to produce energy."

As with caffeine, your response to these potent compounds will be individual and James advises experimenting during training sessions to see if it's right for you; ''Half a litre of beetroot juice is about the right dose, or you can now buy handy shots that are more concentrated and often more palatable! Blood levels peak after 2-3 hours, so time your intake according to when you're looking to boost performance."

Keeping a close eye on your nutrition will improve your workouts no end. Read more expert tips from James Collins.

This article was last updated on 25 March 2019.

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.


How do you fuel for fitness? Do you have any go-to snacks or recipes that help you to get the most from your workouts? Share your tips with us in the comments below...

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