Why does our stomach growl?

Answer: Digestive muscles contracting

Digestive muscles contracting ✓ — Correct! Stomach growling, called borborygmi, happens when digestive muscles contract in waves called peristalsis. These contractions move food, fluids, and air through your intestines. When your stomach is empty, the contractions squeeze mostly air, creating louder rumbling sounds. Hormones like motilin trigger these contractions, especially when you're hungry.

Food is fermenting inside — Wrong. Food fermentation by gut bacteria does produce gas, but stomach growling is caused by peristaltic muscle contractions moving contents through the digestive tract.

Stomach acid bubbling — Wrong. Stomach acid doesn't bubble to create growling sounds. The noise comes from peristaltic contractions of smooth muscles squeezing air and fluids through the digestive system.