Yes, what we are talking about today is the hoax of the week, because it is being talked about widely. Also on social networks, of course, but above all among people who are familiar with each other, not to mention families.
It is said of waking up at dawn to then go to the beach and be able to afford a morning dip. Or of parents who, like coaches of professional athletes, keep their noses on the hands of the clock and give their children the green light only after the fateful two hours have passed (which, depending on the places and traditions, can rise to three or more).
In short, we are talking about the urban legend (indeed, seaside) according to which, after eating, you have to wait two hours to be able to swim.
Is this statement true or false? And if it’s false, why?
Take a bath after eating. Yes but ate How much?
Before analyzing the question from a scientific point of view, let’s rely on logic.
By saying that it is necessary to wait two (or more) hours before taking a bath after eating, a rigid limit is established. This could at best make sense if even that “after eating” were quantified precisely. Let’s explain better: what’s the point of saying that you have to wait two hours regardless of how much and what you ate? Really should the wait be the same if I had breakfast with a yogurt or if I just came from a wedding dinner?
The congestion
Once a certain compliance has been shown on the logical side, let’s try to address the sentence in its overall sense.
The gist of the speech is: taking a bath after eating is dangerous because digestion is in progress, and therefore a sudden change in temperature can lead to congestion.
First, it is good to agree on the term congestion. Which indicates a slowdown in digestion during strong temperature changes. But beware: a first sign is given by the fact that congestion it is not a medical term.
Let’s say it right away: there is no scientific evidence that taking a bath without waiting the legendary two hours after eating leads to congestion. Of course, a strong temperature leap in the most intense phase of digestion could create physical problems, but it is enough to use common sense.
And if you really can’t give up a dip in icy water after having swallowed three hundred grams of peperonata, do like the professional divers, who take a cold shower to acclimatise before taking a dip. The authoritative pediatric magazine Uppa also reminds us of this.
Nothing different from going out lightly covered on a winter day after a hearty meal: the blood goes towards the peripheral areas of the body to maintain the right temperature, decreasing the flow necessary for the correct digestive process.
Digestion and intense physical activity
The example of the divers serves us to clarify the waiting time before taking a bath after eating.
It’s not the water (unless, we repeat, it’s particularly cold and you stuffed yourself the moment before) that is hostile to digestion, but intense physical activity.
As we stated above, digestion requires an abundant blood supply. The same required by intense physical activity. If you expect to go for a kilometre-long swim, as well as a vigorous and long run or pedal ride, after two pizzas and three tiramisu, it will not be difficult for you to feel unwell.
The writer of these lines is an amateur runner, and in the environment there is a rule (which, of course, must then be calibrated on individual habits and characteristics). Usually, it is not recommended to exercise earlier than one and a half hours after breakfast, and before three hours after lunch.
So, going back to the water: if I’ve just eaten and I’m soaking to relax, I’m safe. If I pretend to set the world record for the nautical mile, I may suffer some inconvenience.
Commonplaces and common sense
The myth of waiting two hours before taking a dip in the sea falls into the large category of myths and traditions that are handed down because “it has always been done this way”, without ever wondering on what scientific basis.
It is much better, as we said, to rely on common sense, and to know that intense physical effort “steals” precious blood for digestion. But does anyone really want to swim like Federica Pellegrini after swallowing two cheeseburgers and half a liter of Coca-Cola?
We are rather safe on the possible shock given by the sudden change in temperature: the Mediterranean is an averagely warm sea, and the difference with the air temperature in the summer months is never very high.
Rather, the problem really shouldn’t arise, because in the summer – when we tend to get dehydrated more easily – we need to eat light meals, preferring foods rich in water such as fruit and vegetables.
And in any case, after a lunch on the beach, read a good book.