Swimming is a great workout for the whole body and an enjoyable way to keep fit and healthy. As a competitive sport, swimming can involve a mixture of endurance and sprint training, depending on distance. Competition races can last anywhere between 20 seconds and 15 minutes and may involve multiple heats over the course of a day. This presents some unique challenges for swimmers when it comes to fuelling the body – read on to find out more.


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Young man swimming the front crawl in a pool

Why is swimming nutrition different to other forms of exercise?

If you're new to swimming, eating properly and at the right times may help to develop your strength and cardio fitness more quickly. If you compete in the pool, fuelling for training is vital for optimal performance.

The main fuel for any form of exercise is carbohydrate, this is stored in the muscles and liver as glycogen but we can only store a relatively small amount, which is why keeping levels topped up is important. It's difficult to eat and digest food both close to and during swimming, which is why emphasis is placed on eating before and after to maintain energy stores, especially if you swim more than once a day.

How long after eating should I wait before I swim?

Everyone has different levels of comfort regarding eating around swimming, so it's important to trial what works for you. In general, allow 2-4 hours before your swim if you’ve eaten a larger meal, and 30 minutes - 2 hours following a small snack.

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What should I eat before I swim?

When choosing what to eat, consider the Glycaemic Index (GI) – this is a measure of how quickly a carb-based food is digested and broken down into energy (glucose). Lower-GI foods give a more sustained release of energy and should be the focus of your main meals during training. High-GI foods are quickly broken down and are more readily available for energy, these make great snack options before, during or after training and when ‘carb-loading’.

As a general rule, focus your main meals on low-GI carbs along with moderate amounts of protein and fat.

Take a look at these delicious options:
Brown rice stir-fry with coriander omelette
Barley, chicken and mushroom risotto
Chicken, butter bean and pepper stew
Smoked haddock with lemon & dill lentils
Tofu scramble

Often work or other commitments will dictate when you can get to the pool, meaning that only a quick snack before your swim may be possible. For energy-boosting snacks, try to focus on smaller, higher GI carbs that will be quickly absorbed and place less strain on the gut.

Useful options include:

  • 500ml bottle of commercially available isotonic sports drink
  • 1.5 carbohydrate energy gels
  • Small handful of jellied sweets
  • 1 large banana
  • 1 large cereal bar or carb-based energy bar (low fibre)
Three bowls of apple & linseed porridge, with a jar of honey

What should I eat when swimming first thing in the morning?

If you're going for a swim first thing, or have a training schedule that starts very early in the morning, fuelling your body for the task ahead can be a challenge. The horizontal body position in the pool makes gastric influx more of an issue, so it's impractical to consume large amounts of food close to training – something you might get away with if you were cycling or running.

That said, if possible, aim to eat something before your morning swim, especially if it's longer than an hour in duration or is a high-intensity session. The body uses carbs stores for high-intensity work, so if you train on an empty stomach, you might find you tire more quickly. Many recreational and competitive swimmers find eating before swimming difficult because they experience symptoms of reflux or even nausea in the pool.

Here are two ways to plan:

1. The early riser

If you wake up 2 hours before your swim, try one of these tasty options:

Apple & linseed porridge
Honey muesli with raspberries & hazelnuts
Smoked salmon & pea frittata
Banana yogurt pots

2. Straight out of bed

If you prefer to get straight down to the pool, the energy-boosting snacks above make good options or try one of these delicious options:

Kiwi fruit smoothie
Apricot & seed protein bar
Fruit leather

If you can’t tolerate any food before your swim, try increasing the carbs in your evening meal the night before, as this will be stored in the muscles as glycogen, ready for your morning swim.

What food should I avoid before a swim?

In order to provide sufficient fuel, you need to be choosing foods that are predominantly high in carbs, that you are accustomed to eating and know you tolerate well.

In the 2-4 hours before your swim, aim to limit the following because they're known triggers of gastrointestinal distress (diarrhoea, bowel upsets):

  • Excess fibre
  • Very fatty foods
  • Spicy foods
  • High levels of caffeine
  • Alcohol

In the hour before a swim, snacks should be more easily absorbed, high-GI carbs and contain limited amounts of fibre.

We like these tasty options:
Raspberry, almond & oat breakfast cookies
Breakfast muffins
Healthy pumpkin muffins

Raspberry, almond & oat breakfast cookies

Can energy gels play a part in my fuelling strategy?

Yes, they can – you’ll see that we refer to energy or carb gels in our recommendations for pre-swim snacks. These products provide a convenient, concentrated source of carbs which makes them a useful alternative to whole foods for training sessions. However, when you are not training always opt for nourishing, whole foods in preference because of the wider nutrition they provide.

Most energy gels provide a fast-digesting (high-GI) source of carbs (about 20-25g) in the form of sucrose, fructose, glucose or maltodextrin. The secret to successful fuelling is to take the gel just before you need it.

Whichever fuelling strategy you adopt, be sure to trial it in training, because digestive issues are highly individualised.

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

What to eat during your swim
What to eat after your swim
What to eat during your run
What to eat after your run

Are you training for an event this year? Share your tips and experiences below.

This article was reviewed on 4th 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.


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