Science says that eating before taking a dip in the pool is quite okay. "It's absolutely fine to go swimming any time after you eat," says Peter Wernicki, an orthopedic surgeon at Cleveland Clinic Indian River Hospital and a member of the Red Cross Scientific Advisory Council.
Although, myth says that eating diverts the blood towards the stomach and away from the muscles which can result in paralyzing cramps.
Inadequate blood supply can very much cause muscle cramps. When we eat, the body diverts the extra blood to our stomach which when we exercise goes to the muscles. However, the change in blood supply after eating an entire sandwich isn't so severe that you result in a medical emergency.
Eating before swimming isn't remotely dangerous and there hasn't ever been a recorded instance of a person drowning just because they ate food before going for a swim. Although, drowning is still a danger. According to the Centers for Disease Control and Prevention, it was from 2005 to 2014 when an average of 3,536 people died due to drowning which makes it about 10 deaths per day. The cause of drowning can be due to holding your breath for too long under the water or breathe too deeply right before diving in. Eating is nowhere related and so you should stop believing in all the myths related to it.