The war on junk food is forging ahead . New York, Philadelphia, and Boston have banned trans fats . New York is forcing restaurants to post calorie counts . Britain has outlawed junk-food ads during kids’ TV shows. South Korea’s capital has banned soda from schools. Berkeley and other jurisdictions have prohibited new fast-food restaurants in certain neighborhoods, and last year, Los Angeles considered doing the same .
When I first outlined this crusade, I said it would rely on three arguments : that we should protect kids, that fat people are burdening the rest of us, and that junk food isn’t really food. All of those arguments are certainly in play.
But a fourth argument has joined the mix as well: Junk food, like cigarettes, is addictive and should be similarly regulated. Initially, this was just a metaphor. Now it’s becoming more than that. Scientists are trying to show that food literally addicts you like drugs.
Two days ago, Alain Dagher and colleagues from the Montreal Neurological Institute published a study in Cell Metabolism on the effects of ghrelin, a hormone associated with appetite. They concluded that “metabolic signals such as ghrelin may favor food consumption by enhancing the hedonic and incentive responses to food-related cues.” The word addiction never appears in the journal article, but it’s all over the spin and the coverage. Here are excerpts. Keep an eye on the phrases I’ve bolded.
First, the press release from Cell Metabolism :
The reward centers linked to ghrelin in the new study are also those involved in drug addiction. “That shows it’s reasonable to think of high-calorie food as having addictive potential,” Dagher said. If so, he suggests that the results could provide the basis for new policies aimed at treating fast food more like cigarettes —for instance, banning its sale in school cafeterias.
Here’s the press release from MNI :
The study supports the view that obesity must be understood as a brain disease and that hunger should also be looked at as a kind of food addiction . Obese individuals may eat too much largely due to excess hunger. Dr. Dagher and colleagues found that ghrelin worked on regions of the brain known to be involved with reward and motivation, the same regions implicated in drug addiction . … “These areas work together to assign incentive value to objects in the world and to actions, and exert very powerful control over our behavior . They are all targets of addictive drugs (like cocaine and nicotine) , and are also targets of feeding signals like ghrelin,” explains Dr. Dagher. … This research may also inform public policy. If food is thought of as potentially “addictive,” this would support action to limit or ban fast food from schools and junk food advertisements geared toward children, in the same way that results proving nicotine to be addictive spurred the current public policy toward nicotine.
In the Telegraph of London, Dagher links tobacco, cocaine, and chocolate :
Interestingly, the brain response to smoking pictures (in smokers) is very similar to the brain response to food pictures. In a previous study from our research unit, the brain response to eating chocolate was similar to the response to cocaine (in cocaine addicts). Finally, the evidence that high calorie foods are, in a way, addictive (something soft drink and fast food merchants have known for years) provides a justification for public policy.
In fact, Dagher suggests that food addiction may be the basis for drug addiction, rather than the other way around. Here’s his interview with LiveScience :
“One theory is that addictive drugs act on brain systems designed to control food intake ,” Dagher said. “Our brains didn’t evolve to make us vulnerable to addictive drugs.” Neuroscientist and psychologist Dana Small at the John B. Pierce Laboratory affiliated with Yale University, who did not participate in this study, said these findings suggest it might make sense “to use what we know about drug addiction to understand and treat obesity .” It may be reasonable to think “of high-calorie food as having addictive potential,” he added. ” If food can be thought of as ‘addictive,’ this supports doing things like banning fast food shops from schools, or advertising junk food to children. Note that public policy aimed at tobacco was really spurred by the science showing that nicotine was addictive.”
In a HealthDay wire story, Dagher combines the addiction and harm arguments to make a direct case for regulating food like tobacco:
[I]t makes sense to think of appetite as a kind of addiction. So, if we want to address the fact that obesity is now the number one killer in the world, we’re going to have to tackle the problem in the same way that we tackle cigarette smoking .
Scientifically, the evidence for food addiction isn’t nearly this simple. Endocrinologist Barbara Kahn points out :
Overeating and drug addiction may converge on some of the same neurons. But other pathways are also involved. And from a biochemical point of view, the two are not the same thing. Drug addictions are much stronger. So to suggest that they are the same makes people feel that they can’t do anything about overeating. That it’s out of their control. So, I don’t really buy that parallel. There may be aspects of overeating that may be related to aspects of addiction. But overeating is not just another addiction.
As a scientific matter, I suspect that Kahn is right and that Dagher is overselling the data. But as a media matter , simplicity beats complexity, and a good metaphor wins every time. Just look at the headline on New Scientist ‘s report: ” Stomach hormone turns hungry people into junkies .”
As neuroscientists focus their attention on obesity, you can expect to see more studies comparing food cravings to drug addiction. As these studies accumulate, you can expect to hear them cited in campaigns to regulate junk food. But the people pushing this analogy had better hope the science is exaggerated. Because if we really do crave junk food the way addicts crave drugs, good luck prying those cheeseburgers from our hands.
