Hunger is usually accompanied by a noisy stomach growl. Even the smell or thought of food can increase the growling and grumbling in the stomach. What causes the stomach growl?

Hunger and appetite are controlled by a complex nervous and hormonal system. When the food supply in the body decreases, hormones are released by the digestive system that activate the hypothalamus in the brain. This awakens the appetite, i.e. the desire to eat, and one actively begins to search for food. As soon as the hypothalamus receives the signal, acids are produced in the stomach and the muscles in the stomach contract. The interaction of digestive juices and muscle contraction causes the noisy growl from the stomach. 

Stomach growling is most common when hungry, but can occasionally be heard after eating due to the digestive process. Excessive stomach growling can be an indication of indigestion. Usually, however, other symptoms such as diarrhoea, flatulence, stomach cramps and bloated belly also occur.