Junk food elicits addictive behavior in rats similar to the behaviors of rats addicted to heroin, a new study finds. Pleasure centers in the brains of rats addicted to high-fat, high-calorie diets became less responsive as the binging wore on, making the rats consume more and more food. The results, presented October 20 at the Society for Neuroscience’s annual meeting, may help explain the changes in the brain that lead people to overeat.The study’s coauthors, Paul Johnson and Paul Kenny of the Scripps Research Institute, fed the control group a high-nutrient, low-calorie diet, and fed the other group standard “junk food” fare, including Ho Hos, sausage, bacon, and cheesecake. The results are shocking, even scary.
According to the ScienceNews article, rats on the junk food diet “soon developed compulsive eating habits and became obese.” They also took in twice the amount of calories as the control rates. And “after just five days on the junk food diet, rats showed ‘profound reductions’ in the sensitivity of their brains’ pleasure centers. . . . As a result, the rats ate more food to get the same amount of pleasure.” This is similar to heroin addicts, who become habituated to the drug and need to take increasingly larger doses to feel good.
The most shocking result of the study, however, was how strong the drive to eat junk food became for the rats:
The researchers exposed the rats to a foot shock when they ate the high-fat food. Rats that had not been constantly exposed to the junk food quickly stopped eating. But the foot shock didn’t faze rats accustomed to the junk food—they continued to eat, even though they knew the shock was coming. “What we have are these core features of addiction, and these animals are hitting each one of these features,” Kenny says.This study has implications for all of us. It is a cautionary tale of sorts, revealing the dangers of a diet full of processed foods. I know it has caused me to reflect more seriously about my diet, which often consists of highly processed foods from campus vending machines. Also, the study provides valuable insight into the neuroscience of junk food. I was reminded of an interview of Dr. David Kessler, former commissioner of the Food and Drug Administration and author of The End of Overeating: Taking Control of the Insatiable American Appetite. He and several other colleagues did a study that also evaluated the neuroscience of eating, which found that what he calls “hypereating” is a “behavior that is both conditioned and driven.” We can say to millions of Americans who have a hard time resisting their food in front of them, it’s not their fault,” Kessler says. “There’s a biological reason for why it’s so hard to resist.”
At first I thought it might be too strong to say “it’s not their fault,” because people can choose what to eat, right? But as I thought about it, I considered how difficult it is to avoid food that contain fat, sugar, and sodium, or anything that doesn’t have a list of a dozen incomprehensible ingredients. And as I mentioned in my blog post last week, U.S. food policy makes ingredients like high fructose corn syrup practically inescapable. So unless you have the time and resources to grow and cook all own food, you are vulnerable to becoming addicted to processed foods. I’d say we need to change some things.
As was mentioned in previous blog posts, Shepard Smith argued that taxing a product means it “will be with us till the end of the world.” Smith’s argument, however, was that we would become addicted to the tax revenues. As it turns out, the real problem is that we can become addicted to the product itself. So, is regulation a better solution than taxation? And how much regulation is necessary? If junk food really is as addictive as heroin, it seems that completely banning it would be necessary. We often say that junk food is okay every so often, but we wouldn’t say the same of heroin. But the food and beverage industry would probably have enough power to squelch any movement toward that, and it would probably be unpopular with Twinkies-loving (and possibly Twinkies-addicted) consumers as well. Also, it would be difficult to decide on what counts as a junk food and should therefore be banned—would we base it on how much sugar, or fat, or cholesterol, it has? would we base it on the processing it goes through?
If you ask me, the real solution to this problem is serious reform of U.S. food policy to make processed foods less ubiquitous and make healthy, local food more possible. However, the farm bill isn’t up for renewal until around 2013, so I think that a soda tax would be worthwhile—but it should be implemented with more long-term strategies in mind. Also, I think the food and beverage industry and the agricultural industry has a serious responsibility to create and sell products prudently. In the aforementioned Kessler interview, Kessler said, "Have they [the food industry] understood the neuroscience? Have they understood how fat and sugar work? I don’t think so. But we now have that science. But what’s important is the fact that they have figured out—they’ve learned it experientially—what works, and they construct food to stimulate us to eat more." Now that there is further evidence to suggest that food can be designed and packaged to be addicting, I hope that company leaders choose to be responsible and ethical rather than manipulative and destructive.
Finally, a quick note on media coverage. In my research, I was amazed to see how many news sites reported on the study's findings (I first read this article from Grist, which was well-written, and even the U.K.'s Telegraph reported on it). Then I decided to search the phrase "junk food rats" on Twitter and was amazed to find pages upon pages of people tweeting and retweeting the study's findings. Although many articles get tweeted, it's impressive that a study that hasn't even been published yet—it was only presented at an academic conference—has already received so much media attention.
