Eating is Addictive

The next few updates will likely focus on the topic of fat loss and food psychology, which I guess is fitting as its now May and a lot of you guys are shifting focus away from bulking season and towards cutting in order to get into beach-shape. A lot of you will already be a month into it. This update will detail just why you crave awesome food. And by awesome I mean ‘junk’. But it’s still awesome.

First things first, I just want to get out of the way the more obvious fact that when you diet your brain responds by increasing appetite hormones and making you crave food. But there is something else afoot, and that is the so-called ‘reward system’. This is a system that gives pleasure in return for indulging in certain behaviors. It is the way the body implements learning and reinforces behavior that it deems as desirable. This includes the obvious quest for food and procreation (sex feels great, obviously). But also envisage the feeling you get when breaking a PR, hitting a homer, scoring a touchdown, winning money on the lottery and generally doing anything that invokes some sort of pleasure (I won’t go into details as there are some whack-jobs on the internet that derive pleasure from some weird things and places). The hormone that governs this system is dopamine, which is released in response to the positive behaviour making you feel good and establishing connections in the brain. So the way it goes is that you do something the brain likes and it releases dopamine making you feel good. You now know that to feel good like this again, you have to repeat the feat, leading to a conditioned response and repeat behavior.

Euphoric drugs hit this system hard, causing sudden and large amounts of dopamine to be released. This really throws a wrench in the works, messing up the reward circuitry of the body permanently in frequent users. Hyperactivation of the system results in decreased output, so future activations require higher doses to elicit the same effect. This is a downward spiral that is incredibly hard to get out of. Once at this stage, there isn’t much an addict won’t do in order to get the next fix.

Researchers have made the same connection with the drive for food held by obese rats, showing a similar state of disrepair to their reward circuitry. Just like in a drug addict using bigger doses more often, obese rats develop compulsive overeating habits. Even when the researchers started coinciding pain from electric shocks with the eating, they persisted, and when they exchanged the junk food for salad, the rats simply refused to eat illustrating just how conditioned the rats were to obsessive eating. The researchers believe this same pattern of behavior is evident in obese humans, showing why they persist to eat in the face of ill-health and disease. I’d like to think that obese humans would be a little smarter than to continue to try and eat despite receiving shocks, but honestly, who knows.

So next time you see a commercial on TV for Taco Bell and start reminiscing how awesome your last one was, and how you could just go for one right now, you know this is a conditioned response that your brain has installed driven by dopamine. Incidentally, when you diet for prolonged periods of time, dopamine tends to drop quite dramatically. Along with the rise in appetite and hunger hormones I noted at the beginning of the article, it is this lowered output of the reward system that drives you towards high-calorie junk foods. This is one of the many ways in which the body manages to keep you alive, and has kept the human race going for so long.

Source: Johnson PM, Kenny PJ. Dopamine D2 receptors in addiction-like reward dysfunction and compulsive eating in obese rats. Nat Neurosci. 2010 May;13(5):635-41.