Why does your stomach growl when you are hungry?

When you haven't eaten for a while, your brain signals the digestive system to prepare for food by contracting the muscles in your stomach and small intestine. These contractions push air, gas, and any remaining fluids through the digestive tract, creating the rumbling or growling sounds known as borborygmi. The process is actually the same one that moves food through your digestive system after a meal, but when your stomach is empty, there's nothing to muffle the noise. The growling can also happen after eating, but it tends to be louder when empty because food and liquid normally absorb much of the sound.