Pain whether it’s physical or emotional is controlled by your brain in the hypothalamus. The hypothalamus is responsible for regulating your hunger, thirst, response to pain, levels of pleasure, sexual satisfaction, anger and aggressive behavior, and more. It also regulates the functioning of the autonomic nervous system (see below), which in turn means it regulates things like pulse, blood pressure, breathing, and arousal in response to emotional circumstances.
You can control how much or little pain your in. Interestingly that the hypothalamus also handles hunger & levels of pleasure including pleasure from food.
In one of the more recent discoveries, it seems that there is a protein called leptin which is released by fat cells when we overeat. The hypothalamus apparently senses the levels of leptin in the bloodstream and responds by decreasing appetite. It would seem that some people have a mutation in a gene which produces leptin, and their bodies can’t tell the hypothalamus that they have had enough to eat. However, many overweight people do not have this mutation, so there is still a lot of research to do!
Sudip Das's Blog 