Holiday parties are coming soon and your visceral fat pads could not be happier. We all know the routine: a conversation begins while standing next to the buffet table and mindless eating commences. We repeatedly tell ourselves that we should stop eating and move away from the buffet line and let someone else get at the food. Our bellies are full to the point that it hurts to breathe. Why can't we stop eating when standing next to a long table set out with a delicious and beautifully arranged selection of holiday foods?
Neuroscientists have some interesting explanations. One of these is call ingestion analgesia. The role of ingestion analgesia is to defend eating from ending. Even though continued eating becomes unpleasant because your stomach is painfully stretched to its full capacity, you've reached the point where you cannot unbutton anything else in public, you've embarrassed yourself in front of the relatives or co-workers by your voracious appetite, etc.; yet, you still keep noshing. Essentially, we block out the painful feedback from these feelings by releasing endogenous opiates into our brain and body. Scientists have discovered that our reaction to pain is significantly reduced when eating tasty foods, such as chocolate. This explains why we can indulge in a decadent dessert even after we've become fully satiated by a large meal. We've basically become insensitive to the pain of continued eating.
Sadly, our bodies do not stop there. Even after we've gained a lot of weight, our bodies want to gain more. Recent research indicates that obese humans have elevated levels of endogenous endocannabinoids, i.e. marijuana-like chemicals, in our blood and brain. Remember the munchies? When we become overweight our bodies induce a constant state of the munchies by bathing our brain in endocannabinoids. In addition, these endogenous cannabinoids actually contribute to the ingestion analgesia thus allowing us to feel less emotional and physical pain while overeating.
Our brains evolved when food was scarce; thus, we are compelled by our genetic legacy to eat whatever and whenever possible. Humans become hyperphagic, i.e. the tendency to eat a great deal of food, when palatable food is readily available. Not only that, we tend to subconsciously prevent others from taking our food source. According to a study published last year in The Journal of Neuroscience, we defend our access to tasty food when it is within easy reach and is at risk of being consumed by other humans. Recent studies have shown that humans will eat more when more food is available even when the food is stale or otherwise unappealing (which is good news for bad cooks!). Furthermore, even if you point out to someone that the food is stale or that they've eaten more than their fair share, they will continue to eat. Our biological drive to consume tasty foods to completion outweighs any opposing cognitive or motivational factors.
Ingestion analgesia is just one more reason why you should never underestimate the power of food upon your brain.
© Gary L.Wenk, Ph.D. author of Your Brain on Food (Oxford, 2010); http://faculty.psy.ohio-state.edu/wenk/
See also: Marijuana and Coffee are Good for the Brain. http://www.youtube.com/watch?v=2uVXs6CY2ps