Are "ultra-processed" foods addictive? Some scientists say yes, pointing to experiments with sugar-craving rats and the difficulty many people have losing weight and keeping it off. Taken in isolation, these observations lend themselves to a food addiction model, but there's actually little evidence to support the theory.
After being obese for most of my life, I finally made the decision to get in shape in my early 20s. It took a little fine-tuning to figure out a diet and exercise routine that I could live with, but once I did, the excess weight consistently fell off over the course of a year or so. It was a trying experience to so drastically change my lifestyle, but at no point did I feel like I was battling an addiction to junk food and couch surfing. I simply determined that I wanted to lose weight, then I did.
I bring up my experience because I've seen many psychologists and nutritionists argue for years that “addictive” foods high in fat and sugar drive the obesity epidemic by hooking people and preventing them from making healthier choices. Writing in The Conversation last week, University of Michigan psychologist Ashley Gearhardt made this case, emphasizing that ultra-processed foods have a lot in common with illicit drugs:
Ultra-processed foods are highly reinforcing – they can shape your behavior to keep you coming back for more … In rats, researchers have repeatedly found that sweet tastes are more reinforcing than even highly addictive drugs, like cocaine. The high failure rates of diets make it painfully clear that ultra-processed foods can trigger strong, often irresistible urges to use despite a desire to quit.
I don't buy it, and neither should you. This narrative is based on inappropriate comparisons between food and truly addictive substances like nicotine. It also requires us to ignore a lot of contrary evidence going back many years.
How do you diagnose food addiction?
A food addiction diagnosis is based on similarities between behaviors related to overeating and the criteria used to diagnose substance addiction. This is appealing as an analogy, but it introduces lots of problems right off the bat. While most people don't use drugs abusively, everybody eats, and food doesn't exert the same pharmacological effect that drugs do. Therefore, it is very difficult to diagnose food addiction because you can't easily distinguish someone who misuses an addictive substance from someone who doesn't.
With the above considerations in mind, how do you quantify that someone's sugar consumption indicates addiction? The Yale Food Addiction Scale attempts to measure factors like distress and impairment related to overeating and withdrawal symptoms like anxiety or agitation. But the process becomes subjective rather quickly as you try to measure the severity of these reactions without actual evidence that certain foods or their ingredients are addictive.
The problem is compounded because there is significant (though imperfect) overlap between the symptoms of food addiction and binge eating disorder (BED), which is characterized by “eating-related cognitive distortions, shape/weight concern, and dietary restraint ...”—not substance dependence. How BED and food addiction are related appears to be an open question, but considering them side by side still complicates the food addiction-obesity narrative. As Medical News Today observed in June, some existing evidence shows that:
"a substantial number of individuals with BED do not have obesity and that most people with obesity do not experience disordered eating or food addiction symptoms."
Sugar worse than cocaine?
What about those sugar-addicted rodents Gearhardt mentioned? Such studies seem to indicate that animals can get hooked on flavorful foods the same way they develop a taste for cocaine. But the key question is, do these animal models translate to humans living in the real world? No, not really.
For instance, if you locked me in my office and gave me a choice between organic carrots and Burger King, I'd eat the Whopper every time. If you shocked my foot to discourage my burgeoning burger habit, I'd probably eat more of them just to spite you. Rhetoric aside, the point is that experiments in artificial conditions are bad proxies for human behavior in the environments we actually inhabit. A pair of obesity researchers made the same point more eloquently in a 2012 paper:
"These models do validate some of the predictions from the neuroscientific model [of food addiction]. However, the findings, while they tell us that hyperpalatable foods, administered in particular, often highly constrained regimens, produce an addiction-like syndrome, they do not afford easy translation to humans who are not subject to such constraints … But the question remains: do humans, in their very different environments, become truly addicted to certain nutrients?"
Spoiler alert: their answer was no, though they acknowledged that better data could change this conclusion in the future. Other scientists have reached the same conclusion.
Lots of loose ends
My colleague Dr. Chuck Dinerstein has pointed out that there is a mismatch between our metabolism and the modern environment. "Nature didn’t design us for Big Macs and remote control of the television, we are out of sync." That's certainly true, but there are several clear indications that we can surmount the temptation to binge watch Tiger King and subsist on McDonald's, further complicating the food addiction narrative.
For one thing, people can develop cravings for foods or ingredients that are not palatable, which undermines the claim that “ultra-processed” creations like chips and candy bars uniquely fuel addiction. Some clinical research has also found that giving obese patients a drug like naltrexone will reduce their interest in palatable food but won't promote weight loss.
Perhaps most importantly, studies have shown that people can lose weight and keep it off long-term by monitoring their caloric intake and body weight and regularly exercising. Planning meals and measuring food have the same positive effect. Choosing the right diet makes a difference, too, since people often see similar results on very different regimens.
All of this suggests that cultivating self-awareness through appropriate lifestyle changes allows us to overcome the supposedly “addictive” properties of processed foods. Accordingly, some researchers have argued that obesity treatment should address the behavioral component of overeating while avoiding the unsubstantiated claim that some chemical or chemicals in food can spur a substance use disorder.
Conclusion: food snobbery abides
Food addiction doesn't help explain overeating in any meaningful way. Although the “ultra-processed” meme is contradicted by plenty of evidence, it survives because it offers a chic explanation for why “the unwashed masses,” to use one food scholar's phrasing, continue eating cheap, convenient, and, by the way, often nutritious foods.
People aren't rational creatures with complex motivations and backgrounds on this view; they're victims whose free will and health have been undermined “in the service of profits” by a duplicitous food industry, as Gearhardt claimed. Naturally, she argued, “it will likely take industry regulation to chip away at the popularity of ultra-processed foods and the health problems that come along with them.”
That's not science; it's food snobbery dressed up in academic language. The Conversation should quit promoting it.