You might have heard that you should wait 30 to 60 minutes after a meal to go swimming. But where exactly did this idea come from? And does it hold any truth?
While your parents may have listed out many reasons why swimming on a full stomach was a big no-no, the evidence that there’s danger in hopping back into the pool immediately after lunch is scarce.
We’ll look at where this pervasive myth came from and the actual science of swimming post-meal.
Where did the idea come from?
While it’s not clear when the idea first took, the rule has been printed in several earlier editions of the Boy Scout handbook, as well as a swimming book from the early 1900s.
In a 1967 edition of the guide, “Wait 1 hour after a meal before going in the water,” is listed as one of the “commonsense rules of water safety.”
Similarly, a 1967 volume of Outdoors U.S.A., Yearbook of Agriculture, lists waiting to swim post-meal as a rule. “Don’t swim when overheated, overtired, or right after eating.”
Years earlier, in her 1918 book, “How to Swim,” author Annette Kellermann wrote, “A period of at least 2 hours should elapse between eating and entering the water, in order to give the digestive processes time to get their work well underway.”
What are the claims?
After a big meal, blood flow is diverted away from your working muscles and into your stomach to help with the digestion process. This is in opposition to during exercise when blood flow shifts away from your stomach toward your working muscles and lungs.
The thought seemed to be that if your blood was sent toward your stomach, there wouldn’t be enough left for your muscles, leaving them oxygen-deprived, potentially causing you to cramp up and drown.
What does the science say?
As for the evidence that proves eating before taking a dip is dangerous? It’s weak. We’ll go over what actually happens after you eat a meal, and then dive into the research surrounding the prevalent myth.
What happens after you eat a meal?
When you eat a meal, your body breaks down the food into nutrients it can use. This is called digestion. But, how does it work? It’s a rather complex process, but the basics are as follows: nutrient breakdown starts in your mouth with chewing and ends in your small intestine. The walls of the small intestine absorb nutrients into the bloodstream then the blood delivers the nutrients to the rest of the body. The remaining waste passes through your large intestine, where water is taken out and used by your body.
To help this process take place, blood is redirected from other parts of your body to your stomach and gut. This is where the claim comes in. Because blood is redirected, some thought there wasn’t enough left over for the rest of the body. But, the truth is, we have enough blood to keep all our body parts functioning after a big meal.
The research around swimming after you eat
In a 1961 research bulletin published in the Journal of Health, Physical Education, and Recreation, exercise physiologist Arthur Steinhaus wrote, “It is surprising that a rule of this kind has been so long recommended for rigid enforcement without any scientifically valid evidence.”
Steinhaus described the guidelines as “questionable.”
In a 1968 study, 24 swimmers were fed a carb-heavy breakfast of cereal, toast, sugar, butter, and whole milk, and then were instructed to wait for varying periods of time before swimming laps. None of the swimmers reported any cramping or nausea no matter when they were tasked with swimming post-breakfast.
More recently, after a deep dive into the existing literature, a 2011 review published by the American Red Cross found that there was no danger to swimming after eating.
One thing to note: While there’s little evidence to suggest much risk in swimming after eating, swimming after drinking alcohol is a real danger.
Alcohol use is involved in up to 70% of deaths associated with water recreation among adolescents and adults, according to the Centers for Disease Control and Prevention (CDC). Alcohol can decrease a person’s balance, coordination, and judgment, and it increases risk-taking behavior. For these reasons, alcohol and water activities should not be mixed.
What about eating and exercising after, in general?
Eating and exercise have an important relationship: The body needs food as fuel to perform its best, but eating the wrong food or eating at the wrong time can affect the body’s ability to function at its best.
To fuel up for a workout, the American Heart Association recommends eating 2 hours beforehand. But what to eat? Here’s what they have to say:
- Drink water. There are no exact rules to how much, but the American Academy of Family Physicians recommends 17 to 20 ounces (a little over 2 cups).
- Eat complex carbohydrates. Whole grains are a great choice, as are beans and brown rice.
- Avoid fatty and slowly digested foods. Saturated fats, such as those found in butter, cheese, and red meat should be limited. So should large amounts of protein as they take a while for your stomach to digest.
So, can I swim after eating?
Do your thing! Swimming after eating should be fine, as long as your body feels comfortable and the swimming is recreational — as in, just for fun.
If you’re doing some extreme exercise, however, you’ll probably want to be thoughtful about what you put into your body. And remember, mixing alcohol and water activities is never a good idea.
By Kate Bratskeir