The stomach is the biggest bulge in the digestive tract, as most of us are well aware. But it is located higher than you might think, lying mainly behind the lower ribs, not under the navel, and it does not occupy the belly. It is a flexible bag enclosed by restless muscles, constantly changing form. Virtually nothing is absorbed through the stomach walls except alcohol. Watery substances, such as soup
, leave the stomach quite rapidly. Fats remain considerably longer and an ordinary meal of carbohydrate, proteins, and fats is emptied from the average stomach in three to five hours.