A yearlong study of 46 children suggests that brain responses to tempting food images may partly explain the link between ultra-processed diets and increasing body fat.
Ultra-processed foods account for about 67% of the daily calories consumed by children in the United States. Although these products have been linked to weight gain and other health problems, scientists are still trying to understand how they may interact with the developing brain. New research suggests that children who eat more ultra-processed foods show stronger brain responses to appetizing food images, and those responses are associated with increases in body fat one year later.
Ultra-processed foods (UPFs) include products such as certain breakfast cereals, packaged breads, and instant soups. They are manufactured to be appealing, convenient, and shelf-stable, often containing artificial sweeteners, colors, and other ingredients not typically used in home cooking. Previous studies have linked UPF consumption to weight gain, type 2 diabetes, and cardiovascular disease, but the role of the brain’s reward system in these associations remains unclear.
Childhood may be an especially important time to investigate this relationship because the brain is still developing and food preferences are taking shape.
“Children’s brains are still developing, habits are still forming, and food preferences are still being made. It’s an important period where the brain is very sensitive to food and the food environment,” said study senior author Kathleen A. Page, MD, professor of medicine and pediatrics and co-chief of the Division of Endocrinology and Diabetes at the Keck School of Medicine of USC. “We’re particularly interested in understanding these processes in children, because we believe that intervening early could make a real difference.”
Brain scans reveal stronger reward responses
To explore how UPF consumption relates to brain activity and weight gain, researchers studied 46 children between the ages of seven and 10 who were enrolled in the long-term BrainChild study, which investigates diabetes and obesity risk. All participants began at a healthy weight, allowing the team to examine potential early signs of increased risk.
At the beginning of the study, researchers used magnetic resonance imaging (MRI) to monitor the children’s brain activity while they viewed pictures of appealing foods, including cookies and French fries. The team also collected information about each child’s diet, body mass index (BMI), body fat percentage, and waist circumference. BMI is a measurement based on height and weight. One year later, researchers measured BMI, body fat percentage, and waist circumference again.
The brain scans revealed that children who consumed more UPFs had stronger responses to food pictures in the dorsal striatum, a brain region involved in reward and motivation. Children with stronger responses in this region also tended to experience greater increases in BMI and body fat percentage over the following year.
Brain responses may help explain weight gain
By the end of the study, children who had consumed more UPFs also had higher BMI, body fat percentage, and waist circumference. The researchers then examined whether differences in brain activity could help explain these relationships.
When they statistically accounted for how strongly each child’s dorsal striatum responded to food images, the association between UPF consumption and BMI weakened by 31%. The association with body fat percentage weakened by 44%. These findings suggest that the brain’s sensitivity to appealing food cues may help explain part of the relationship between UPF consumption and changes in body composition.
“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.”
The findings, published in JAMA Network Open, provide evidence of a possible connection between diet, reward-related brain activity, and subsequent changes in body fat. The research was funded in part by the National Institutes of Health.
Whether diet changes the brain remains unknown
However, because the study was observational, it cannot establish that eating UPFs directly changes brain activity or causes weight gain. The results also do not determine whether stronger brain responses lead children to consume more UPFs or whether their diets influence how the brain responds to food.
To investigate cause and effect, Page hopes to conduct an intervention study in which children who regularly consume UPFs are provided with more minimally processed foods. Researchers could then examine whether changing their diets alters their brain responses to food images over time and whether those changes are associated with less weight gain.
The researchers also emphasize that improving children’s diets cannot depend entirely on individual families. Ultra-processed foods are often among the most affordable, convenient, and accessible options, making dietary changes difficult without broader improvements in food availability.
“Changing the food environment to help people access healthier, more minimally processed foods is an important part of the solution,” Page said.
Meanwhile, the BrainChild study will continue following participants through puberty and into young adulthood. By tracking changes in brain activity, body composition, diet, and overall health, researchers hope to better understand how eating habits during childhood relate to health later in life.
Reference: “Ultraprocessed Food Intake, Striatal Response to Food Cues, and Adiposity Gain in Children” by Jasmin M. Alves, Ella Morgan, Brendan Angelo, Kianna Le, Jared Smith, Ting Chow, Kay Jann, Anny H. Xiang and Kathleen A. Page, , JAMA Network Open.
DOI: 10.1001/jamanetworkopen.2026.40252
This research was supported by an American Diabetes Association Pathway Accelerator Award [1-14-ACE-36]; the National Institute of Diabetes and Digestive and Kidney Diseases of the National Institutes of Health (NIH) [R01DK116858, R01DK134079]. The REDCap database used for this study was supported by the Southern California Clinical and Translational Science Institute [NIH UL1TR001855].
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