Normal human behavior dictates that we seek out activities which bring us pleasure or are rewarding, and thus contribute to our sense of well-being. The underlying system in your brain which is responsible for that subjective experience of pleasure is known as your Endogenous Reward System.

A key word here is endogenous, which means having an internal cause or origin.  That’s a critical concept and we will return to it in a moment. Your subjective experience of pleasure refers to the fact that we all get varying amounts of pleasure depending on the activities that we enjoy. This  experience is totally individual; for some people it might be reading a book, other people might prefer interacting with their friends, and of course almost everybody relishes eating the foods that they like. 

These gratifying experiences are produced in one the older parts of the brain, sometimes called “the mammalian brain”.  The scientific name for this region is the “limbic system”.  Located deep inside the brain, the limbic system is responsible for the feelings and emotions we experience from our body.  It is intimately involved with learning and memory.  Our limbic system basically works to tell us how we “feel about something” so that the cortical area of the brain knows how to think about it or do so something about it.

The Limbic System contains two structures, commonly called the “pleasure centers” of the brain. These structures are called the ventral tegmental area and the nucleus accumbens septi. Don’t worry about the names, basically what this means is that if you were to look at images of your brain then these areas would show a lot of activity when you are having a pleasurable experience. The crucial point here is that these pleasure centers are in close and constant communication with the more evolutionarily advanced area of your brain (the primate brain). Within this area there are two regions, the prefrontal cortex and the orbitofrontal cortex, that are very involved with our planning and actions. It is pretty obvious that if your limbic system tells your cortex that an activity is pleasurable that your cortex would want you to act by doing it again or planning to do it again!  

Here is the really important piece. Biochemically, the neurotransmitter dopamine is used to communicate between these various parts of your brain (there are others, but dopamine is the major player). Dopamine is an endogenous neurotransmitter which can be translated to mean “self-made drug”. Drug you say? Yes your brain makes drugs, and lots of them!

Typically, when we think of drugs we mean substances that we ingest or inject. In medical terms these would be referred to as exogenous drugs. But we now know that we also have endogenous drugs. For the sake of simplicity let’s call the exogenous drugs man-made drugs. So we have self-made drugs and man-made drugs. An example of a man-made drug is cocaine, a drug that induces your brain to release dopamine. Typically dopamine is a chemical released in certain areas of the brain when we experience something as pleasurable.  So cocaine produces the same feeling in your brain but doesn’t require you to do anything (except take the drug in one form or another) in order to get pleasure.  So dopamine is a “self-made” drug that makes us feel very happy or euphoric and cocaine is a man-made drug that does the same thing but it does so by cheating.

The problem that we now face is that we are often relying on man-made drugs rather than self-made drugs to allow us to feel pleasure. Nowhere is this more evident than in our relationship with food. Can food act like a drug? Absolutely. When we eat food our limbic system releases some dopamine into those pleasure centers. It’s a good strategy, your brain needs to reward you for eating food because it is essential to your survival. For most of humankind’s history food wasn’t necessarily very easy to come by and we needed the extra incentive of a reward to motivate us to pursue it.  So it has been very important for our survival to have these self made drugs.  They give us incentive to work hard for things that may not be immediately available because we anticipate a reward at the end.  But in today’s world, acquisition of food has really changed.  Not only is it readily available it is prepared, packaged, plentiful and palatable… it requires so little work we barely have to chew it! But our brains still compel us to seek reward, especially if we are stressed. So we engage in behaviors that stimulate production of those self-made drugs. 

This however, is not the whole story. Our physiologic well being is geared towards alway trying to maintain balance or equilibrium.  The medical term for this is homeostasis and it is essential to our health and survival.  Our endogenous drugs are designed to help us maintain homeostasis.  Exogenous drugs can easily upset this balance. Exogenous drugs stimulate your pleasure centers with unnatural intensity.  This can result in addiction which means balance is lost and pleasure seeking or reward seeking turns to pathological craving.  Modern day food offers a lots of convenience but are also highly stimulatory to our pleasure centers.  The food industry knows how your brain works and one of their major goals is to chemically enhance foods so they are more attractive to your pleasure centers. Think about it, when you eat a food that makes you produce self-made drugs and also contains man-made drugs, it acts as a super charged blast to the pleasure centers of our brain. We are in a sense programmed to pursue and consume. These altered foods taste delicious and make us feel better, so we are much more likely to eat them again.

Over the coming week, we are going to take a closer look at the food industry and how you can become addicted to food, just like you would to any other drug.