"Nothing gets me high as that sandwich cookie does. But I love the filling most. I rub it on my roast, mix it in with my coffee, and spread it on my toast. I love the white stuff, baby. In the middle of an Oreo."
—Al Yankovic, "The White Stuff," 1992
The rat stands in a plastic maze. At the end are two rooms, each decorated in its own unmistakably unique, gaudy fashion. The rat knows them both. Inside one room, he has received injections of morphine or cocaine. In the other, he's gotten injections of a saline placebo. The rat has learned to prefer the drug room.
He even chooses to lounge in the drug room after the injection supplies have dried up. It's kind of like how you might hang out in the parking lot outside of an old high school, remembering the glory days; or at the apartment of an ex-lover, befriending the new tenants. Your ex-lover is dead, but it still feels good.
This is a paradigm called conditioned place preference. It's a standard behavioral model used to study the Pavlovian rewarding and aversive effects of drugs. Dr. Joseph Schroeder's rats are not pioneers.
Schroeder is an associate professor of psychology and director of the behavioral neuroscience program at Connecticut College. Last year, Jamie Honohan was a senior student researcher in Schroeder's lab and scholar in the college's Holleran Center, which focuses on social justice issues, public policy, and community action. Honohan was interested in the obesity epidemic—specifically, why there is more obesity in urban, low-socioeconomic-status populations, and the role of a lack of nutritious food.
So Honohan came to Schroeder with an idea for some research based on the rat conditioning model. What's a thing that both rats and humans like? Sewers, tunneling, hammocks, ... Oreos. That's it. Oreos are also cheap calories, widely available, and contribute to the obesity epidemic. Would feeding Oreos to the rats in this model have the same conditioning effect as giving them drugs?
Honohan, Schroeder, and some other students designed an experiment. In terms of behavior, the Oreos did it. The rats trained with Oreos spent just as much time in the Oreo room—as opposed to a boring rice-cake room, even after there were no Oreos or rice cakes—as did the rats trained with cocaine or morphine.
Then the researchers went a step further.
What if we cut open their brains, too, they wondered.
"We examined the nucleus accumbens," Schroeder explained to me, "which is the brain’s pleasure center. We measured the expression of a protein there [c-Fos]. So it basically tells whether that brain center is being turned on or not in response to a behavior. And we found that there was a greater number of neurons that were activated in the brain’s pleasure center in animals that were conditioned to Oreos compared to animals that were conditioned to cocaine [or morphine]."
"What that indicates," Schroeder says, "is that, perhaps, high-fat, high-sugar foods are stimulating the brains in the same way as drugs of abuse and can be considered as a potentially addictive substance."
That concept has been shown before, but remains important. In a 2010 study published in Nature Neuroscience, rats who spent 40 days eating bacon, sausage, cheesecake, and frosting—someone please market that combination; I mean please don't—became "addicted." They continued eating even in the face of electrical shocks. Non-addict rats did not. The researchers, at Scripps Research Institute in Florida, likened the brain activity in the addict rats to that of cocaine and heroin addicts.
"We make our food very similar to cocaine now," commented an unmoved Dr. Gene-Jack Wang at the time. Wang is a biomedical imaging researcher at Brookhaven National Laboratory. "[Now] we purify our food," he said. "Our ancestors ate whole grains, but we're eating white bread. American Indians ate corn; we eat corn syrup."
Wang also drew an interesting parallel between the social roles of processed food and cocaine. People have chewed coca leaves for 4,000 years, but the pure cocaine alkaloid was not isolated until the mid-19th century. It was more potent and addictive. American manufacturers were quick to put it in everyday products.
Like junk food, the ubiquitous coca extract products came to be most notoriously abused among underprivileged populations. Civil unrest and white panic around "negro cocaine fiends" at the end of the 19th century played a role in the removal of the alkaloid from Coca-Cola and its criminalization shortly thereafter. A century later, the still more potent, cheaper crack cocaine hit ghettos so disproportionately that African-American leaders like California representative Maxine Waters called for a Department of Justice investigation into the possibility that the drug's introduction was a CIA plot against inner-city black Americans.
The plot this time, according to journalist Michael Moss in Salt Sugar Fat (among others) has been squarely attributed to a manipulative food industry—companies like Nabisco, Kraft, General Mills, Mars, etc.—formulating products that play on "the hidden power of some processed foods to make people feel hungrier still."