Your stomach is a temporary storage tank. Empty, it holds less than a child’s juice box does. Swollen with food, it expands a staggering 30 to 50 times— large enough to accommodate nearly a gallon of food and drink.
Your stomach is also a muscle—one that few of us have trouble exercising. It expands and contracts continually, kneading, twisting, compressing, and mixing your food with powerful gastric juices that help digest it. The more food you put in your stomach, the more vigorous the mixing. When your stomach is empty, you might hear the noisy rumbles that biologists call borborygmus (pronounced “bore-bo-rig-mus”), but you call growling.
As your stomach churns your food, the meal gradually takes on the consistency of a creamy paste. Roughly three times a minute, your stomach squirts out a small eyedropper’s worth of this paste into your small intestine (which is the next stage in the digestive journey). In this way, your stomach slowly works through your breakfast, preparing it for further digestion, being careful not to hurry the job and overwhelm your intestines.
Your stomach passes along almost all the food it receives. However, some substances can dissolve through the thick coating of mucus that lines your stomach and enter your blood. Examples include alcohol and certain drugs, like aspirin.
It usually takes 2 to 4 hours for your stomach to empty itself. Fluids and carbohydrates pass through it quite quickly, while protein takes longer, and fat forms an oily layer that’s digested still more slowly. Large, fatty meals can linger for 6 hours or more. In the sample breakfast meal used here, the last holdout is the sausage, which supplies half of its calories from fat. For that reason, the sausage is also the most likely part of your meal to return as heartburn
Ideally, you’ll eat food that won’t race through your system or overstay its welcome. If you eat meals that have a dash of unsaturated fat and a good dose of fiber, you’ll process them steadily but gradually, and you’ll feel full longer. You’ll also avoid the sudden sugar rush and insulin release that raw carbohydrates cause—a process that can, over the years, encourage diabetes.
Source of Information : Oreilly - Your Body Missing Manual