The process of muscle contractions moving food along the digestive track through various organs is the primary cause of a growling stomach, according to HowStuffWorks. Some other conditions that cause a growling stomach include hunger, an upset stomach or a medical condition.
The result of the process of muscle contractions continuously moving food downward through the body is called peristalsis, and this causes the stomach to growl, notes HowStuffWorks. Moving along with solid and liquid ingredients are pockets of air and gas that can be heard as growling. If the small intestine or stomach contains food, the growling is quieter. When the stomach empties itself, the brain signals for the process of peristalsis to begin, causing a growling stomach. The medical condition of irritable bowel syndrome can cause excessive gurgling and grumbling.
Incomplete digestion of carbohydrate-containing foods, including gluten, dairy products and whole grains, can lead to excess gas in the intestine, explains Wikipedia. In fewer instances, diarrhea and constipation can cause stomach growling and excessive abdominal noise. Stomach rumbles can also occur in the gastrointestinal system when air is swallowed while talking, eating and drinking. Carcinoid neoplasm and coeliac sprue are two examples of diseases associated with a growling stomach.