10 foods that runners should avoid

Find out what to eat before a run, what to eat during a run and what to eat after a run.

1. Spicy foods

Capsaicin is the active component found in spicy ingredients such as chilli peppers, hot sauces, chilli powder and paprika. Once digested, spicy foods like curries can cause irritation in the body, leading to heartburn, indigestion and gut problems. All are unpleasant side effects at the best of times, but during a run, they can feel even worse and may even stop you in your tracks. In the 24 hours ahead of a run, give your digestion some slack and stick to milder foods, particularly if you don’t usually eat spicy dishes.

2. Too much fibre

Fibre is an important part of a balanced diet for everyone, including runners, as it has a key role in gut health. But there’s a time and a place to eat fibre-rich food – and that time is typically not before a run. As fibre-rich foods move through the digestive tract they produce gas, which can cause pain and bloating. At worst, it can lead to ‘runner’s stomach’ – stomach cramps and diarrhoea – which is something you’ll want to avoid when running outdoors.

Fibre-rich foods include beans, lentils, brassica vegetables including broccoli, apples and wholegrains. These are all brilliant foods bursting with nutrients – just eat them post rather than pre-run.

3. Sugar-free sweets and treats

Some sweeteners used in ‘sugar-free’ food and drinks can lead to gastro-intestinal (GI) issues. Known as polyols, these sweeteners include sorbitol, xylitol and erythritol, and they can have a laxative effect if consumed in large amounts. One or two sweets are usually fine for most people, but consuming lots is best avoided before running or you might find yourself sprinting to the nearest loo.

4. Prunes and dried fruit

Dried fruit is full of natural sugars, which is great for energy but also contains lots of fibre, which can lead to GI issues. Some runners who prefer to fuel naturally may use dried fruit in place of artificial energy gels, however it’s important to only consume a small quantity and track how it affects your digestion. Fruits like apples, prunes and apricots contain sorbitol which when mixed with fibre has a laxative effect – so are best avoided before and during a run.

5. Alcohol

Alcohol is a diuretic and leads to dehydration, which is the opposite of what your body needs for running: hydration. Even a small amount of dehydration affects running performance and can also lead to muscle cramps and fatigue.

6. Energy drinks

While caffeine is found in some energy gels designed for runners, this amount is carefully calculated to aid running performance. In contrast, the amount of caffeine found in energy drinks such as Red Bull is much higher and could adversely affect your running performance. The cardiovascular system is already under pressure when you run, so consuming these drinks could also dangerously affect your heart rate.

In general, sports drinks are only required for longer or more intense runs. Always look for specially formulated sports drinks (or make your own), which will help to replenish electrolytes lost through sweat and supply carbohydrates to restore energy. After a run as you rehydrate, avoid caffeinated, alcoholic or excessively sugary drinks, as these are likely to increase dehydration.

7. Dairy products

Dairy foods such as yoghurt, cheese and milk aren’t a problem for all runners, but can lead to uncomfortable issues for some. If you suspect these foods are an issue for you, try plant-based alternatives to see if they help. Keeping a food diary can help you to identify if there are any problem foods that affect your running.

8. Fried foods

Fried foods are high in saturated fats, which are known to lead to health issues over the long term when eaten regularly. When it comes to fried foods and running, while there’s nothing wrong with treats every now and again, be aware that it takes the body longer to digest high fat foods and can leave you feeling sluggish as a result. These foods can also lead to digestive discomfort, and as such they’re not a wise food choice ahead of a run.

9. Packaged snacks

Running can make you ravenous, and your body may need extra calories to cope with the extra energy demands being placed on it. The trick is to choose wisely: processed snacks filled with calories, added sugar and saturated fats rarely offer the nutrients your body needs to stay healthy. Eaten regularly, they may also lead to weight gain over the longer term, which can affect your running performance and increase the load on your joints as you pound the pavements. Opt for lower salt and sugar options, whole fruits and nuts, and avoid highly processed foods.

See our ideas for healthy sweet snack recipes.

10. Anything new before a big race

The morning or night before a big race or long training run is not the time to try new foods. Experiment with your meal choices and fuelling strategies during the training weeks to find out what works for you – whatever the distance you plan to run, the aim is to have the energy to perform well and to feel comfortable.