Stomach growling occurs simply because of the way the digestive system works and whilst it can be embarrassing, it is usually a good indication that everything is in working order. Although digestion is a very complex and many step process, most of us are familiar with the basic digestive route: mouth>oesophogus>stomach>small intestine>large intestine>rectum (strictly speaking digestion actually starts in the head, where just the very thought of food can stimulate saliva and the production of digestive enzymes!).
Would You Like Fries With That?
Understanding why the growling occurs requires a little trip through the digestive system, so let’s start with a delicious hamburger and a coke! You’ve found yourself in the local burger joint because hormones, which control your appetite, have signalled to the brain via the nerves in your gut that it is time to eat again. The brain responds by instructing the digestive system to begin contracting (peristalsis) and these contractions are the hunger pangs and growls that have forced to you enter the burger joint (it would just take too long to walk all the way to the salad bar).
After wolfing down your favourite burger and soft drink, the digestive machine now has to transport the food all the way through the system, breaking it down into ever smaller pieces and extracting nutrients. It does this by constantly contracting, churning the food and pushing it along the tract, which means more growling! Whilst eating, small amounts of air and gasses will have found their way into the stomach and these will create more noise as they are squeezed through the tract.
The mega rumbles, the ones that seem to strike during job interviews/intimate moments/at the library (insert as appropriate) occur between 1.5-2 hours after eating when the digestive system performs its ‘housekeeping’ duties. The technical name for it is ‘migrating motor complexes’ and they are basically a powerful barrage of contractions, during which any residual food and/or build-up of (harmful) bacterial populations are swept out of the stomach. It’s one very noisy housekeeper!