Junk food junkies

Food for thought

Let’s face it: America has become a junk-food nation.

Junk food

If only junk food were good for you. (Image: iStock.)

If you are a typical consumer, the chances are nearly two-thirds of your diet is made up of highly processed foods.

Think about it. Bagels and donuts for breakfast. Pizza and burritos for lunch. Burgers and fries for dinner, topped off with a scoop of chocolate ice cream. And don’t forget the cookies, candy bars, and cupcakes that seem to pop up almost everywhere, including your neighborhood fitness center.

“We are the epicenter of the people who create, market, and export these highly processed foods,” says Ashley Gearhardt, associate professor of psychology. “Our junk-food environment is so powerful in the U.S. that the default behavior is to eat unhealthily.”

Little wonder that Americans’ waistlines are expanding like beach balls, and diet-related diseases, such as diabetes, are increasing among children and adults. But that’s not all.

Abusive behavior

Ashley Gearhadt

Ashley Gearhardt, Ph.D.

Gearhardt has identified another serious health hazard associated with binging on junk food. In some individuals, eating an unhealthy diet full of sugar, fat, and salt may trigger addictive-like symptoms, including withdrawal.

“There is some evidence that highly processed foods might cause adaptations in the brain that resemble and mimic the effects of drugs of abuse,” says Gearhardt, who conducts studies on addiction and eating behaviors at the U-M Food and Addiction Science and Treatment (FAST) lab.

Her research reveals that when people cut back on eating highly processed foods, they experience withdrawal-type symptoms similar to those observed in drug addicts who try to kick a nicotine or marijuana habit.

In Gearhardt’s recent study, 231 adult participants reported feeling irritability, tiredness, sadness, and cravings for highly processed foods during the initial two to five days after they quit eating them. These junk-food withdrawal symptoms tapered off after the first week.

“We found that people who showed these psychological withdrawal symptoms had a harder time cutting back on junk food and were more likely to fail in reaching their dietary goals,” Gearhardt says. “As with addictive drugs, these psychological symptoms were the best predictor of relapse.”

Getting hooked

Getting hooked on junk food is pretty easy because ingredients and foods with refined carbohydrates, sugars, and fats push all the right biological buttons in the brain’s reward and motivation system.

“Our brains evolved to find highly caloric ingredients and foods rewarding because we needed the extra calories from sugar and fat to survive famine,” Gearhardt explains. “Now we live in a modern environment where food is plentiful and famine is no longer a threat. However, our brains are still very responsive to highly caloric ingredients and foods, and we find them very tasty and rewarding.”

Junk-food manufacturers market their products aggressively and make sure these items are accessible and cheap.

“Highly processed foods are so much more powerful than minimally processed foods that the brain becomes hyper-activated by junk food and starts ignoring healthy foods,” Gearhardt says. “In addition to delivering a higher dose of rewarding ingredients, many highly processed foods have been stripped of ingredients such as fiber, water, and acid that slow down the absorption of sugar.”

Think about how you feel when you eat a raw apple versus a handful of jelly beans. With the fruit, natural sugar is delivered slowly. With the candy, the refined sugar is mainlined.

Junk food packs an extra wallop of refined carbohydrates and sugar — rapidly absorbed into the bloodstream — causing the body’s blood-sugar level to spike and then crash. Afterward, people consume more junk food to achieve that same rewarding sugar high. And suddenly, they’re hooked.

“These highly processed foods are evolutionarily novel to our brains, and we don’t know how to handle them,” Gearhardt says. “This mismatch is a major reason why we are struggling with junk food.”

Changes in the environment

Our food environment began to change dramatically in the late 1970s and early ’80s, primarily as a result of stronger economic incentives and food-processing advancements. Homegrown potatoes gave way to processed french fries and potato chips. Old-fashioned tap water yielded to a torrent of sugar-sweetened sodas and juices. Fast-food restaurants sprang up everywhere.

Gearhardt speaks to audience

“Our brains evolved to find highly caloric ingredients and foods rewarding,” Gearhardt says.

“The food industry became really good at designing and engineering hyper-rewarding, potentially addictive foods,” Gearhardt observes. “High-fructose corn syrup became cheaper and easier to put into a wide variety of foods. Since then, our entire diet in the Western world has gotten sweeter.”

Food manufacturers also have added hidden sweeteners to staples such as bread, tomato sauce, and ketchup to sway consumers’ food preferences and spending habits. Just check the “nutrition facts” listed on packaged, bottled, and canned foods and beverages, and you may be surprised.

“We are hard-wired to like sweet tastes, so we’re more prone to buy a food item that is sweeter, even if we’re not consciously aware of why we’re buying it,” Gearhardt says. “Manufacturers are tucking sweeteners into these foods because it’s a cheap way to increase the sales of a product. But they often try to hide the fact that they are increasing the sweetness levels.”

America’s junk-food culture has spread to other countries, such as China and India, where highly processed foods are now more prevalent and accessible. As a result, public-health concerns have shifted away from malnutrition and refocused on increasing rates of obesity and diabetes.

“We’ve done a study of the number of McDonald’s per capita in countries around the globe,” Gearhardt says. “The best predictor of who will show obesity is the number of Western-style fast-food restaurants in the neighborhood.”

Target: Children and teens

Waitress with customer

Gearhardt’s Food and Addiction Science and Treatment (FAST) Lab replicates a fast-food restaurant. (Image courtesy of FAST Lab.)

These days, junk food ads saturate our media and penetrate our daily lives. Each year, adolescents in the U.S. see approximately 6,000 food commercials that mostly promote calorie-dense, nutrient-poor foods.

“The food-marketing landscape is getting more challenging for parents who want to defend their children against junk food and establish healthy eating habits,” Gearhardt says. “Food advertising used to be limited to television, but now it’s on social media, YouTube videos, school buses, vending machines, and videogames.”

What worries Gearhardt and other psychologists is that kids are being exposed to potentially addictive foods very early in life, and repeatedly. By the time a child is two years old, he or she is more likely to have a sugar-sweetened food or beverage than a piece of raw fruit or vegetable on any given day.

“The food industry targets kids and teens because companies want to hook these young consumers on their products early in life,” Gearhardt explains. “Children’s brains are still developing and changing, so they are more vulnerable to the effects of addictive substances than adults. Ads for junk food get under their skin by activating reward and motivation circuitry in the brain that is also associated with addiction, and this makes them more prone to overeating.”

In a recent study, Gearhardt looked closely at the effects of fast-food commercials on adolescent brains and behavior. She found that teenagers who showed the highest activation in the brain’s reward centers when they viewed food advertisements on television were at higher risk of gaining excess weight over time.

“Kids don’t know their brains are being activated, and parents don’t realize this is happening,” Gearhardt says. “Right now, we are giving the food industry a pass by not advocating for policies to prevent this sort of targeting.”

Kicking the habit

Is it okay to eat a handful of chips or a couple of cookies now and then? How do you know if you’re really addicted to junk food? What steps can you take to kick the junk food habit and adopt a healthier diet for yourself and your family? These are some of the frequent questions Gearhardt hears in her psychology practice.

Fast food worker in the kitchen

A student prepares a snack in the FAST Lab. (Image courtesy of the FAST Lab.)

“It’s normal to have some cravings for junk food and to eat more than you wanted to, because these foods are designed to make you do that,” she says. “If you have the tendency to eat several hundred junk-food calories a day, your consumption may be sufficient over time to increase your risk for obesity and diet-related disease.”

Most people don’t become addicted to junk food. However, some vulnerable individuals are at high risk for developing a full-blown clinical response.

“These people have lost control over their consumption and continue to eat junk food even though they experience negative consequences,” Gearhardt explains. “Their diet causes a lot of psychological distress, such as depression and intense cravings, and starts to impair their ability to function in their daily lives.”

The good news is that the withdrawal symptoms experienced by those who cut down or stop eating junk food may subside after five days. Anyone who can get through the first week and continues eating a healthier diet has a good chance of kicking the junk-food habit.

Take some action

Gearhardt offers other advice for creating a healthy food environment:

  • Keep a personal journal of what you eat and why
  • Find alternative non-food activities such as exercise or playing video games to reward yourself and manage your stress
  • Identify junk foods that trigger your cravings and keep them out of your house
  • Stock up on healthy foods such as apples, oranges, and nuts that you enjoy eating
  • Avoid dining regularly at fast-food restaurants and do more cooking at home

Does Gearhardt indulge in junk food once in a while? She admits she does. “I do eat junk food at times, but I think about my consumption,” she says. “It’s important to monitor your eating habits and consume junk food in moderation.”

Fortunately, Gearhardt sees a shifting tide in U.S. consumer attitudes toward junk food and the companies that make and market it.

“Americans are starting to expect and advocate for a healthier food supply, especially for their children,” she reports. “They also are holding the food industry accountable for trying to make the science confusing and forging chummy relationships with regulatory bodies. These issues affect everybody, not just a small subset of people. After all, we all have to eat.”


  1. Beverly Trebesch - 1986

    I applaud your work, though I contend the psychological component is often down played in many studies/research projects. There are eaters who are A to B people who do not deviate from their pattern. As well as the instant gratification eaters. I feel this is important because for many eating is a stress response/control reaction. I’m an observer of the why reason of eating as opposed to the what and when of eating. I hope a long review of why will assist people understand their food addiction to capture a turn to healthy choices. Beverly,MSW


  2. Lisa Brewer - 1993

    As someone who definitely is addicted to sugar, I’ve experienced the withdrawal symptoms you’re describing. While things get a little easier after 5 days, I find it takes a full 4 weeks for me to truly get my sugar addition under control after a binge.

    I can have a very small amount of sugar (2 alcoholic drinks, one dessert) over the course of 1 or 2 weeks without my cravings being triggered too badly. However, the more frequently I consume them, the more challenging my withdrawal systems. 1 weekend of drinking with my sisters = 1 month of sugar detox for me, even though overall I have an extremely healthy diet, filled with unprocessed foods, fruits and veggies, and I’m of normal weight.

    I think it’s important to realize, how challenging this can be for people. When I realized I had a problem and eliminated all sugar in my 40s, within a week I was craving alcohol in the afternoons. Fortunately after 1 month the cravings virtually stopped.


  3. Joel Wilkinson - 22

    This article fails to describe “the elephant in the room” which is the microbiome. There are an estimated 50,000 species of microbes in our guts (2 pounds worth) who outnumber our human cells 10 to 1. They are the ones making decisions about what/when/how we eat. The fungi (yeast) that love sugar (and create drugs that hormones) get down to normal levels after a week without them. This explains why sugar cravings subside after a few days. You can help diversify the microbiome through probiotics and (raw) pickled foods, avoiding antibiotics/antibacterials when safe, and eating lots of fiber (which is where good bacteria live in your gut). To talk about diet without talking about the good and bad microbes who are making all the decisions is a waste of time (at least that’s what my gut tells me).


Leave a comment: