Greeks have a name for this rumbling and growling – borborygmi the rhythmic contraction of muscles in the stomach and intestines. The digestive system is one long tube that goes from mouth to butt. The food is pushed through this tube, with muscle contractions called ‘peristalsis’. This wave of stomach contractions mixes and churns food, liquid and enzymes. The mixed mass is called chyme.
When the stomach is empty it sets off a reflex of waves along the intestine and stomach muscles, which start contractions.
During long bouts of not eating, a different pattern of movement takes place in the gut, known as migrating myoelectric complex (MMC). Strong waves of contractions which begin in the stomach and pass down to the large intestine (colon) at 90 minute intervals. The purpose of the MMC is to sweep all residual food, gut secretions, bacteria and other debris down the gut to the colon in preparation for cleaning before the next meal.
The movement of gas down the hollow gut resonates in the absence of food and liquid. The stomach rumbles very often but the absence of food makes it louder. Try shaking a full carton of juice – the sloshing is softer than when you shake a carton which is half or less full.
At times excessive noises from the stomach are a sign of gastrointestinal disorder, for example irritable bowel syndrome. The gases do not clear up and the abdomen feels bloated, contractions feel painful.
Sometimes you have rushed to class or meeting without eating and lunch is a long way still, the noises from your stomach can become very embarrassing – take a pencil and with the eraser end, push it firmly in the stomach area. The stomach muscle gets pushed in and miraculously the growling stops. A finger used may also help, but pushing with the hand is of no use.
Sometimes when you feel a growl coming on, take a deep breath and hold your breath till the growl passes. This is not as effective as the pencil which does the trick every time.