MONDAY, Oct. 26, 2026 (HealthDay News) — Ultra-processed foods appear to rewire kids’ brains so they crave more junk food, a new study says.
Pictures of cookies or fries trigger a powerful reaction in the brain reward systems of children who eat more ultra-processed food, researchers reported Oct. 23 in JAMA Network Open.
Those children subsequently have higher odds of weight gain and more body fat, researchers found.
“Children’s brains are still developing, habits are still forming and food preferences are still being made,” senior researcher Dr. Kathleen Page, a professor of medicine and pediatrics at the Keck School of Medicine of USC, said in a news release. "It’s an important period where the brain is very sensitive to food and the food environment."
Ultra-processed foods are mostly manufactured from substances extracted from whole foods, such as saturated fats, starches and added sugars. They also contain a wide variety of additives to make them tastier, more attractive and shelf-stable, including colors, emulsifiers, flavors and stabilizers.
Examples include packaged baked goods, sugary cereals, ready-to-eat or ready-to-heat products, and deli cold cuts.
On average, U.S. children get about two-thirds (67%) of their daily calories from ultra-processed foods, researchers said in background notes.
Past studies have linked ultra-processed food to weight gain, type 2 diabetes and heart disease, but it’s not yet clear how these foods promote cravings, researchers said.
For the new study, researchers analyzed data from 46 children taking part in a long-term study of diabetes and obesity risk. All the kids started the study at a healthy weight.
Researchers collected MRI scans of each child as they viewed photos of ultra-processed foods and gathered data on the kids’ diet, body fat percentage, waist circumference and body mass index (BMI). BMI is an estimate of body fat based on height and weight.
Results showed that kids who ate more ultra-processed foods had stronger responses to food images in the dorsal striatum, a brain region involved in reward and motivation.
Stronger dorsal striatum responses were also associated with increases in BMI and higher body fat one year later, researchers said.
Overall, children who ate more ultra-processed food had wider waists, higher BMI and more body fat by the end of the study, the study found.
Much of that was linked to brain response to food, researchers said. When researchers accounted for differences in dorsal striatum responses to food images, the association with BMI and body fat weakened by 31% and 44%.
“This study goes beyond just understanding that UPFs affect weight gain,” Page said. “It actually gives us insight into the neurobiological underpinnings by which these foods may be linked to body composition over time.”
Because this study was observational, it can’t prove a cause-and-effect relationship between ultra-processed foods, brain activity and weight gain, researchers said. It can only show a potential link.
To test cause and effect, Page is planning a follow-up study in which kids who regularly eat ultra-processed foods are provided healthier meals and snacks. Researchers can then track their ongoing brain responses to food images and see if that affects their weight.
“Changing the food environment to help people access healthier, more minimally processed foods is an important part of the solution,” Page said.
More information
Columbia University has more on ultra-processed foods and health.
SOURCE: Keck School of Medicine of USC, news release, Oct. 23, 2026
Copyright © 2026 HealthDay. All rights reserved.