Overeating: The Science

In June 24, 2009, I published the following post alerting readers to the combination of 3 simple ingredients that made food “addictive”.

Conditioned Overeating: Fat, Sugar & Salt

“‘Highly palatable’ foods -- those containing fat, sugar and salt -- stimulate the brain to release dopamine, the neurotransmitter associated with the pleasure center, he found. In time, the brain gets wired so that dopamine pathways light up at the mere suggestion of the food, such as driving past a fast-food restaurant, and the urge to eat the food grows insistent. Once the food is eaten, the brain releases opioids, which bring emotional relief. Together, dopamine and opioids create a pathway that can activate every time a person is reminded about the particular food. This happens regardless of whether the person is hungry.”

Now we have the science! 

In Nature Neuroscience

Dopamine D2 receptors in addiction-like reward dysfunction and compulsive eating in obese rats

Paul M Johnson & Paul J Kenny

Published  28 March 2010

 

Lentivirus-mediated knockdown of striatal D2R expression./ Nature Neuroscience

Summary:  We found that development of obesity was coupled with emergence of a progressively worsening deficit in neural reward responses. Similar changes in reward homeostasis induced by cocaine or heroin are considered to be crucial in triggering the transition from casual to compulsive drug-taking. Accordingly, we detected compulsive-like feeding behavior in obese but not lean rats, measured as palatable food consumption that was resistant to disruption by an aversive conditioned stimulus. Striatal dopamine D2 receptors (D2Rs) were downregulated in obese rats, as has been reported in humans addicted to drugs. Moreover, lentivirus-mediated knockdown of striatal D2Rs rapidly accelerated the development of addiction-like reward deficits and the onset of compulsive-like food seeking in rats with extended access to palatable high-fat food. These data demonstrate that overconsumption of palatable food triggers addiction-like neuroadaptive responses in brain reward circuits and drives the development of compulsive eating. Common hedonic mechanisms may therefore underlie obesity and drug addiction

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 Girl in a Chemise circa 1905 Pablo Picasso (1881-1973)
Tate Collection