Can Obesity Be an Addiction?

Bret S. Stetka, MD; Nora D. Volkow, MD


July 16, 2013

In This Article

The Addiction Overlap

Medscape: What neurophysiologic changes occur resulting in addiction?

Dr. Volkow: I, along with my colleagues at Brookhaven National Laboratory and the National Institutes of Health, have been studying the changes in the brain dopamine system in people who are addicted and also in morbidly obese individuals. Generally speaking, when dopamine activates D1 receptors in the reward system, it increases the drive to participate in a rewarding behavior (eg, eating), whereas D2-receptor stimulation helps dampen and regulate this response, allowing us to exert control over the behavior. What we are seeing in addictive behaviors and in obesity is that signaling through the D2 receptor system is markedly attenuated. As a result, you lose your brakes while the engine just keeps going.

What is very interesting is that addicted patients seem to be hypersensitized to stimuli related to, for example, food or drugs. A surge in dopamine activity occurs in anticipation of the reward but drops markedly with actually participating in the behavior. So it's the anticipation that is rewarding, and not so much the reward itself.

Medscape: Very interesting. Presumably, this is only one of multiple potential causes of obesity, correct?

Dr. Volkow: Yes. Obesity can also result from lack of physical activity or from enhanced energy efficiency, such that little energy is required by the cells of the bodies to perform their functions. Even if your peripheral homeostatic signals are working fine, if you live a completely sedentary lifestyle, you still may become obese if you are consuming a greater quantity of calories than you need. So the potential addictiveness of food can contribute to or cause obesity, because it drives our consumption of food even when we are not hungry and our body has all of the nutrients it needs.

Medscape: In your mind, then, would the subset of obesity caused by addictive mechanisms qualify as an addiction?

Dr. Volkow: It's interesting, because in the past we would always say either you have something or you don't; either you're addicted or you're not. However, the new classification system in the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5)[1] has a dimensional component that assesses addiction on a continuum. I think the exact same concept applies to food.

Addiction is characterized by loss of control in relation to a substance or behavior. Now, I lose control over certain foods all the time; however, I am not obese. You could say I have a vulnerability to the rewarding effects of certain foods. But is it severe enough to be called a disease? Probably not. So I would say that in extreme cases of obesity -- in which patients want to stop eating but they just can't, even with awareness of all the adverse physical and psychological consequences (obese people are stigmatized, which is a powerful social stressor) -- then yes, I would say there is an addictive dimension to their behavior.


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