scientists have rediscovered a bundle of nerves located near the stomach and intestinal track, calling it a "second brain." this may explain why people who fast feel a sense of euphoria, as the intestinal track and stomach relax, these nerves may fire more efficiently than ever. this is a short excerpt from the article.
"Scientists are claiming to have discovered a second brain - in the human stomach.
The breakthrough, involving experts in the US and Germany, is believed to play a major part in the way people behave.
This 'second brain' is made up of a knot of brain nerves in the digestive tract. It is thought to involve around 100 billion nerve cells - more than held in the spinal cord."