Until someone asked me about it yesterday, I had completely forgotten about the childhood ritual of sitting and whining poolside after a meal. Do you really need to keep kids out of the water for a full hour? Is half an hour OK? Ten minutes? Friends, do whatever you want. There was never any health or safety related reason for the rule.
Food won’t give you stomach cramps, and cramps won’t kill you
I tried to track down the origin of this rule, and while I couldn’t find a definitive answer, there was definitely a pervasive belief, going back at least a century, that eating before swimming will cause deadly stomach cramps. In How to Swim, published in 1918, Annette Kellermann wrote:
A period of at least two hours should elapse between eating and entering the water, in order to give the digestive processes time to get their work well under way. If the water is entered too soon after eating, especially when it is at a low temperature, the digestive process is immediately arrested, and this in itself is likely to produce a severe case of cramps, and perhaps result in acute indigestion which may prove serious.
Subsequent research hasn’t been able to confirm this, and in fact competitive swimmers eat before and even during long distance swims. You might not feel comfortable having a huge meal before vigorous swimming, but you wouldn’t do that before you went for a run, either.
You can get cramps from any kind of exercise, typically in the arms and legs. A 1950 study of cramps among swimmers included this gem:
As an interesting sidelight we have made it a practice to ask at all of our classes if any student had ever had a stomach cramp while swimming. To date, after questioning over 10,000 boys, we have not encountered one person who has had one, or one person who claims to have actually seen one. ...This is amazing; to say the least, in view of the large number of drownings allegedly caused by stomach cramps. ...It appears probable that we have been perpetuating, unthinkingly, an invention of newspaper writers, which is no more than a notion, educed by untrained observers, based on the flimsiest of evidence.
Emphasis mine. Blame the newspaper writers if you must, but modern science agrees: there is no reason to think meals increase the risk of drowning or other swimming-related risks.
If you’re going to make up a rule, make it a good one
Some people speculate that it’s convenient to keep kids out of the water so parents can catch a break, but I’d rather just lounge in a chair and let the kids swim than answer “No, not yet” a hundred times.
(One member of the Offspring facebook group mentioned that they like to make the kids wait half an hour for poop related reasons—change that diaper before they go back in. But I’d say the rule is outdated by the time your kids are old enough to wipe their own butts.)
There are other reasons I’ve heard parents give, but most of us are pretty lackadaisical about it. “Oh, your friend has to wait half an hour? OK, you can go back in when they do.” But let me propose a change: if you really want a bullshit rule to keep kids out of the water, feel free to make up a very specific one: for example, sharks. Oh look, they’re gone now.