February 2024

Print this issue


Dr. Ashley Gearhardt on Addiction and Ultra-Processed Foods

Excerpts from our conversation with Dr. Ashley Gearhardt, a psychologist studying compulsive eating at the University of Michigan. 

Many researchers are trying to understand compulsive consumption of ultra-processed foods and what similarities it may share with drug and alcohol addiction. We still don’t know the answer for sure. Dr. Gearhardt is leading studies to better understand this important research question.

NIHNiH: What are ultra-processed foods?

Gearhardt: It’s foods like cookies, salty snacks, baked goods, frozen pizzas, deli sandwiches, and sausages. They’re cheap, they’re convenient, they’re typically shelf-stable, they’re easily accessible, and they’ve been engineered to be hyper-palatable. It’s a broad category. But overall, we see that this category is capturing about 60% of the daily food supply for Americans.

NIHNiH: How do ultra-processed foods resemble addictive drugs?

Gearhardt: A lot of times, people are motivated to consume ultra-processed foods excessively not because they need calories, but because they’re looking to change their mood, get a hit of pleasure, feel less stressed, or reduce their feelings of boredom. And the ingredients that are elevated in ultra-processed foods—refined carbs like sugar, added fats—activate reward centers of the brain in ways that appear to be similar to something like nicotine or alcohol. People commonly experience strong cravings for these ultra-processed foods. It’s one of the big obstacles to sticking to healthier diets. And it’s really engaging some of the same brain circuitry when we’re craving drugs as when we’re craving these ultra-processed foods.

NIHNiH: What about ultra-processed foods makes you think they might be addictive, like drugs?

Gearhardt: We know not all drugs are addictive. It’s drugs that rapidly deliver high doses of rewarding ingredients into the body and into the brain that are addictive. It’s why a nicotine patch that’s giving you a slow, steady dose of nicotine doesn’t have nearly the addictive potential as smoking a cigarette. Eggplant has nicotine in it, but nobody’s eating eggplant addictively to get nicotine. Because it’s not rapidly absorbed into the system, and it’s at a low dose.

When you look at highly addictive drugs, they’re nearly all human-made or at least human-refined. There is no cigarette tree, there is no wine river. We take a leaf, we take a plant, we take a potato, and we alter it, process it, and refine it in a way that rapidly delivers these reinforcing ingredients into the brain. Fruits and nuts don’t give us super-high doses of carbohydrates and fat. They’re not easily digested and absorbed into the system. You get carbohydrates in a banana, but it has fiber, and it has water. And it takes a while to eat, and it takes a while to digest.

Imagine sitting down and binging on a bushel of bananas. One banana, and you feel full. When you get that same level of carbohydrate, but from jellybeans, it’s like the sugar goes right into your gut and into your brain. I think our brain just never evolved to handle this sort of delivery mechanism for these ingredients. The brakes are pretty weak when it comes to telling us we’ve had too much.

NIHNiH: What would your advice be to people who are trying to eat better?

Gearhardt: Right now, we’re kind of like, “just eat these foods in moderation.” And for the people for whom consumption of these foods has become compulsive, it’s like telling people with alcohol use disorder to just find a way to drink in moderation. Especially in a food environment like ours, where you’re constantly being triggered and cued. So I suggest people try to meet themselves with compassion. Our brains are still kind of in the Stone Age. They’re worried we’re not getting enough calories. And our food technology is now designed and engineered to entice you and to make it hard to eat these foods in moderation and to induce cravings. That doesn’t mean you shouldn’t try and change. But you shouldn’t hate yourself for having a hard time in this food environment.