Yes , because what drives the food from the mouth to the stomach and from the stomach to the intestine is not only the force of gravity but the peristaltic movements of the digestive system , a kind of waves that propagate alternating contractions and dilations of the walls. A demonstration that this is so is that astronauts digest perfectly even in weightless conditions.
People with digestive problems are advised not to go to bed immediately after a meal and to allow a reasonable amount of time before going to bed. Those who suffer from hiatal hernia – migration towards the thoracic cavity of part of the stomach and the last esophageal tract – should pay special attention, because they are the ideal conditions for the reflux of gastric material into the esophagus. In these cases, lying down or doing a headstand after eating is certainly harmful.
