Understanding Ultraprocessed Food Addiction

Lay’s Potato Chips debuted their infamous “Betcha can’t eat just one!” advertising campaign in the early 1960s, which may surprise younger readers who remember it from decades later. In fact, the slogan became so iconic that it was revived several times, including in the 1970s, 1990s, and 2000s. It’s a brilliant bit of marketing: A challenge to consumers to buy a bag of Lay’s and test their willpower against the tantalizing power of the (fried) potato. Can you resist the compulsion to keep eating, or will you give in and binge the whole bag? Lay’s wins either way, but they “betcha” that you’ll not just eat more but buy more.

Other snack food campaigns have covered similar ground. Pringles’s decades-spanning “Once you pop, you can’t stop!” is a derivative example, while Klondike’s “What would you do for a Klondike Bar?” evoked irresistibility by showcasing the ridiculous things people would supposedly do for their chocolate-coated ice cream fix.

All those advertisements were so successful that they became part of their respective brands’ core identities. All were also examples of companies not just admitting but outright bragging that their high-calorie products are addictive.

Certainly, many people have felt unable to stop eating a snack at some point. But despite that and decades of addiction-coded marketing, the notion that certain foods may be literally addictive was not widely researched until the 2010s. Since then, Professor Ashley Gearhardt has found that our brains and bodies react to some processed foods in ways that closely parallel the responses to addictive substances like nicotine or alcohol.

In doing so, Gearhardt has become a leading researcher in the new field of ultraprocessed food addiction, a path that began during her first year of graduate school at Yale. While working in an alcohol addiction lab there, she encountered the work of other faculty and students studying rising obesity rates. She was intrigued by the similar experiences of those addicted to alcohol and those struggling with uncontrollable overeating.

“I realized many of the mechanisms I had learned about in my alcohol addiction work looked relevant to this growing obesity epidemic,” Gearhardt recalls. “I saw patients who had binge eating disorder or very severe obesity and were getting evaluations for bariatric surgery. They were telling me, you know, ‘I’m addicted to these foods. I’ve been addicted to cigarettes. I’ve been addicted to alcohol. This feels exactly the same.’”

While still a PhD student, Gearhardt shifted her research focus and co-developed the Yale Food Addiction Scale, which is still widely used by researchers. However, she has since realized the term “food addiction” was a bit of a misnomer: Not all foods tend to trigger addictive behaviors. Instead, such responses are reserved almost exclusively for high-calorie ultraprocessed foods (UPFs), which include things like cookies, candy, pastries, pizza—and of course potato chips.

But what makes some UPFs addictive? Well, Gearhardt says it is often easier to explain that by first examining foods that are not.

“Foods that don’t usually trigger addictive responses include most minimally processed foods—fruits, vegetables, legumes, intact whole grains like quinoa, and so on,” she says. “They also include unprocessed meats like salmon and chicken breast. People rarely binge or eat those uncontrollably. We actually can’t get people to eat enough of them.”

Unprocessed foods, even those that are high in sugar (like many fruits) or high in fat (like raw nuts), generally also include a lot of other things: fiber, water, and so on. The molecular structures of carbohydrates and fats in whole foods also tend to be more complex. That means they take more work and more time for the body to process into glucose. And while some natural foods are high in sugar or high in fat, very few are simultaneously high in both.

In contrast, addictive UPFs often strip away the fiber, water, and other “boring” fillers to deliver concentrated doses of just the “good” stuff: refined carbohydrates, fats, and often both. Moreover, those carbs and fats tend to come in simpler, more bioavailable forms that cause sudden spikes (and crashes) in blood glucose and insulin levels. These intense caloric blasts through the gut, bloodstream, and brain trigger responses in the dopaminergic reward system similar to those caused by nicotine or alcohol (in fact, Gearhardt’s work draws on the groundbreaking addiction research of fellow U-M Professors Kent Berridge and Terry Robinson).

But human behavior is complex. Physiologic and pharmacokinetic data can only suggest that a substance could be addictive. Proving that it is addictive requires showing that people actually get addicted to it. The definition of addiction has evolved over the decades, but Gearhardt explains that a widely accepted formalization is the one used in the landmark 1988 Surgeon General’s report declaring tobacco an addictive substance.

Based on that definition, Gearhardt argues that UPFs are unquestionably addictive.

“When the Surgeon General settled the decades-long debate on tobacco's addictiveness, they identified three key criteria and later added a fourth,” she explains. “First, addictive substances are consumed compulsively. This is seen with UPFs, for example, when diabetes patients can’t stop eating them despite severe health risks like amputations and death. Second, addictive substances alter the brain and mood, and many UPFs like chocolate have dopaminergic effects similar to nicotine or alcohol. Third, addictive substances are reinforcing, as evidenced by people willing to drive miles out of their way to get their favorite UPF. The proposed fourth key criteria is that addictive substances induce strong cravings, a concept that is openly reflected in UPF marketing."

Understanding UPF addiction is crucial. According to the CDC, obesity is second only to smoking as the largest contributor to preventable deaths in the US (1) and is a risk factor for at least half of the CDC’s top causes of death, including heart disease, cancer, stroke, respiratory disease, and diabetes (2). And while obesity poses significant risks to individuals, its sheer prevalence is what allows it to claim so many lives—a relatively recent phenomenon. Prior to the late 1970s, U.S. obesity rates held steady for decades at about 15% for adults and 5% for children (3). However, starting around 1978-1980, obesity rates began rising rapidly. Between 1980 and 2008, adult obesity rates more than doubled to 34%, and rates for children and adolescents more than tripled to 17% (3). And those numbers are still rising: the CDC reported an adult obesity rate of nearly 42% in 2020 (4).

Although cultural changes like sedentary lifestyles and increased screen time may contribute slightly to those numbers, they have largely been ruled out as primary causes (5). Instead, the widespread availability and marketing of UPFs is the most likely cause (5), and the rising obesity rates correlate closely with changes in UPF manufacturing, marketing, and consumption since the late 1970s.

Gearhardt hopes her research will eventually inspire communications and policies like the ones that led to a dramatic decline in smoking over the last few decades. As a result, she is very active in communicating to government officials and the public about her research.

“I hope my work leads to significant impact,” she says. “Testifying before the US Senate was crucial. I also communicate frequently with the media. I think about the consequences if tobacco researchers had not engaged with policymakers or the public; without their efforts, the outrage and pressure for change wouldn’t have occurred. It’s sometimes challenging and stressful to work with the government and media, but it’s essential.”

References:

1) Panuganti KK, Nguyen M, Kshirsagar RK. Obesity. [Updated 2023 Aug 8]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK459357/
2) Leading Causes of Death. CDC.
https://www.cdc.gov/nchs/fastats/leading-causes-of-death.htm
3) Freedman, D. S., PhD. (2011, January 14). Obesity --- United States, 1988--2008. https://www.cdc.gov/mmwr/preview/mmwrhtml/su6001a15.htm#:~:text=From%201976%2D%2D1980%20to,adolescents%20(2%2C3)
4) Adult obesity Facts. (2024, May 14). CDC Obesity.
https://www.cdc.gov/obesity/php/data-research/adult-obesity-facts.html
5) LaFata EM, Gearhardt AN. Ultra-Processed Food Addiction: An Epidemic? Psychother Psychosom. 2022;91(6):363-372. doi: 10.1159/000527322. Epub 2022 Nov 7. PMID: 36349805.
https://karger.com/pps/article/91/6/363/826582/Ultra-Processed-Food-Addiction-An-Epidemic