Children who consume more ultra-processed foods (UPFs) may have stronger brain responses to tempting foods, potentially helping explain why these products are associated with weight gain. A new study published in JAMA Network Open found that children who ate more of these foods showed heightened activity in the brain’s reward system when looking at pictures of appetizing foods. Those stronger responses were also associated with increases in body fat over the following year.
Ultra-processed foods include many everyday products, such as breakfast cereals, packaged bread, and instant soups. They are manufactured to be appealing, convenient, and able to remain fresh for extended periods. Many contain artificial sweeteners, coloring agents, and other ingredients rarely used in home cooking. These products make up a substantial portion of children’s diets, accounting for approximately 67% of the calories consumed by children in the United States.
Previous research has associated ultra-processed food consumption with obesity, type 2 diabetes, and cardiovascular disease. However, scientists are still trying to understand the biological processes that might explain these connections. The new investigation, supported in part by the National Institutes of Health, combined magnetic resonance imaging (MRI), dietary assessments, and measurements of children’s body composition to explore whether the brain’s response to food could play a role.
“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 the study’s 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 a Link to Future Weight Gain
To investigate these connections, the research team studied 46 children between the ages of seven and 10 who were enrolled in the ongoing BrainChild study, which examines factors contributing to diabetes and obesity. Every participant had a healthy weight when the research began, giving scientists an opportunity to investigate potential warning signs before excess weight developed.
At the start of the study, the children underwent brain scans while looking at pictures of appealing foods (such as cookies or French fries). Researchers also gathered information about their diets and recorded several health measurements, including body mass index (BMI), body fat percentage, and waist circumference. After one year, the team measured these physical characteristics again to identify changes.
The brain scans revealed a notable pattern. Children who consumed larger amounts of ultra-processed foods showed greater activity in the dorsal striatum when viewing food pictures. This part of the brain helps regulate reward and motivation, making it particularly relevant to how people respond to desirable foods.
Importantly, children with stronger responses in this brain region also tended to experience greater increases in BMI and body fat percentage over the next year. The findings suggest that heightened sensitivity to food cues may be one factor connecting ultra-processed diets with subsequent weight gain.
How Brain Reward Activity May Influence Body Fat
By the end of the study, children who consumed more ultra-processed foods generally had higher BMI, greater body fat percentage, and larger waist circumference.
The researchers then examined whether differences in brain activity could help account for these associations. When they adjusted their analysis to consider the children’s responses in the dorsal striatum, the relationship between ultra-processed food intake and BMI became 31% weaker. The corresponding association with body fat percentage decreased by 44%.
These reductions suggest that the brain’s reward response may help explain part of the relationship between ultra-processed food consumption and changes in body composition. Although the results do not demonstrate that these foods directly alter brain function, they provide a possible biological explanation for an association that has been observed in previous research.
“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.”
Making Healthier Foods More Accessible
The researchers caution that improving children’s diets cannot depend entirely on individual families. Ultra-processed products are often inexpensive, widely available, and easy to prepare, making them practical choices for households facing financial or time constraints.
“Changing the food environment to help people access healthier, more minimally processed foods is an important part of the solution,” Page said.
There are also important limitations to consider. Because the study was observational, it cannot determine whether eating ultra-processed foods directly causes heightened brain activity or increases in body weight. The findings establish relationships between these factors, but additional research is needed to determine whether one causes another.
Page hopes to address that question in a future intervention study. The proposed research would provide children who regularly consume ultra-processed foods with more minimally processed alternatives. Scientists could then examine whether changing their diets affects how their brains respond to food images and whether any differences are associated with reduced weight gain.
Meanwhile, the BrainChild study will continue tracking participants as they move through puberty and into early adulthood. By monitoring brain development, body composition, dietary patterns, and general health over time, researchers hope to gain a clearer picture of how childhood nutrition may influence long-term health.
Research Team and Funding
The study was led by Page alongside Jasmin M. Alves, Ella Morgan, Brendan Angelo, Kianna Le, and Jared Smith from the Division of Endocrinology and Diabetes, Department of Medicine, and Diabetes and Obesity Research Institute at the Keck School of Medicine of USC, University of Southern California. Additional contributors included Kay Jann of the USC Stevens Neuroimaging and Informatics Institute at the Keck School of Medicine of USC, University of Southern California, and Ting Chow and Anny H. Xiang of the Department of Research and Evaluation at Kaiser Permanente Southern California in Pasadena, California.
Funding came from an American Diabetes Association Pathway Accelerator Award [1-14-ACE-36] and the National Institute of Diabetes and Digestive and Kidney Diseases of the National Institutes of Health (NIH) [R01DK116858, R01DK134079]. Support for the REDCap database used in the research was provided by the Southern California Clinical and Translational Science Institute [NIH UL1TR001855].
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