Depending on what you read. You shouldn't eat 20 minutes, 1 hour or even 2 hours before you go swimming.
The reasons for why you shouldn't eat just before going swimming also vary but are based on the idea that you need to give your body time for digestion to start and for some food to leave your stomach.
- one good reason for not eating just before you go swimming is that it's highly likely to make you feel sick and there is a good chance that you will see said food again. Which obviously isn't ideal.
- secondly if you eat before you swim there is a high chance that you could get cramps. There is a really long explanation of why this happens here. However, the long and short of it is that your digestive system is in direct competition with your other working muscles for blood flow and a lack of blood flow to a certain area will lead to the tissue beginning to cramp (at least I think that's it).
- and finally and slightly worrying I read somewhere that in the long run, putting your digestive system under this undue pressure could lead to higher risks of certain types of stomach/bowel/intestine cancer .
So I don't know about number three but that definitely scares me enough to think that even if it isn't true, why take the risk? So I won't be eating too close to swimming anymore (or when doing any other exercise for that matter). If you read this blog regularly you will probably know that I have had a bit of a problem with cramping in my feet and legs (read about that here). Maybe being prone to cramp has something to do with eating too late before training? Maybe it doesn't? But again I think it's worth making sure that I leave a good amount of time between eating and swimming in the hope that it might cut down on the amount of cramp I suffer from. And finally I know all about number one. Luckily I wasn't sick but a couple of weeks ago I very cleverly ate a whole bag of pistachio nuts before going for swim. Such a bad idea! I felt weak and ill the whole time and had one of the worst swims I've had in ages.
So my advice would be: don't eat just before swimming because of the potential risks but if you absolutely have to eat, make sure it's not a big bag of pistachio nuts.