Not waiting an hour after eating before swimming can cause you to drown
This is a common myth that people still live by, so much so that it sparked a scientific advisory review from the American Red Cross in the International Journal of Aquatic Research and Education. The review concluded with them stating that eating directly before swimming is not a contributing risk for drowning and is a myth. The ‘science’ behind the myth is that the re-direction of blood flow whilst digesting can weaken your muscles and cause you to be too weak to float, another version is that the re-direction of blood flow from your muscles does not occur and instead makes your stomach unable to digest the food causing cramps. The truth behind this fact is actually the opposite, eating before swimming can actually give you a boost of energy and make it easier for you to stay afloat.
Bonus fact: The origin of this myth comes from a 1908 issue of the Boy Scouts handbook, it stated that if boys didn’t wait 90 minutes before swimming they might drown and it “will be your own fault”. Where they found the ‘information’ for this fact is unknown but regardless it has remained a common belief for over 100 years.