Junk Food Diet Causes ‘Drug Addiction’ Like Changes in the Brain

Dopamine is one of the major pleasure regulating neurochemicals in the brain, and when people take heroin or cocaine, it is dopamine that floods the brain and causes intense pleasure.

If a person takes cocaine or heroin regularly, the brain tries to get things back to a normal level of functioning by decreasing the number of dopamine receptors in the brain. Once this happens the drug using person must take drugs just to feel normal – and will experience negative states when not using drugs. Dopamine down regulation causes physical dependency.

Researchers now say that the same thing happens to those that eat too much junk food!

Eating fatty or sugar laden foods causes the release of dopamine in the brain, and thus pleasure. In a laboratory study, rats given regular access to fatty sugary foods for a period of weeks not only gained a substantial amount of weight, they also changed their brain chemistry. They experienced the same dopamine receptor down regulation as is seen in drug addiction.

Lead researcher Paul J. Kenny explained, “When the animal over-stimulates its brain pleasure centres with highly palatable food, the systems adapt by decreasing their activity. However, now the animal requires constant stimulation from palatable food to avoid entering a persistent state of negative reward."

As they lost dopamine receptors, they ate ever more compulsively, and would even brave electric shocks to gain access to sugary or fat laden food. When only healthy food was offered, the ‘food addicted’ rats simply refused to eat at all.

Kenny says that the study results are significant, as they show a neural explanation for overeating, but he says also that there’s really no surprise here, saying, "People know intuitively that there's more to [overeating] than just will power. There's a system in the brain that's been turned on or overactivated, and that's driving it at some subconscious level."

The full study results can be found in the journal, Nature Neuroscience.