The first and most obvious symptom of gastroenteritis is a liquid stool known as diarrhea. It may continue all day long without a good reason. Because of that, a patient is losing a tremendous amount of water. It is necessary to receive the important amount of nutrients anyway. When a digestive system behaves this way, it requires double the amount of usually absorbed nutrients as it wastes more of them than regularly. Pick beverages that contain a lot of electrolytes – these elements will support the body energy.