Children with higher ultra-processed intake show stronger reward signals

USC researchers reported in a JAMA Network Open study publicized Nov. 3 that 46 healthy-weight children ages 7 to 10 with higher ultra-processed food intake had larger reward-system responses.

The small observational study matters because ultra-processed products account for about 67% of calories consumed by U.S. children, and children with larger neural responses recorded bigger gains in body mass index and body-fat percentage after one year.

The research drew on the ongoing BrainChild study, which examines factors linked to diabetes and obesity. Each child had a healthy weight at the start, allowing the team to examine early associations before excess weight developed.

Researchers used magnetic resonance imaging, or MRI, while children viewed pictures of appetizing foods, including cookies and French fries. They also assessed diet and measured body mass index, body-fat percentage and waist circumference at the start and again after one year.

Children with higher intake of ultra-processed foods had more activity in the dorsal striatum, a brain region involved in reward and motivation, when looking at food images. By the end of the study, children with higher intake generally had higher body mass index, greater body-fat percentage and larger waist circumference.

"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 Kathleen A. Page, senior author and professor of medicine and pediatrics at the Keck School of Medicine of USC.

Ultra-processed foods, often described as products made with industrial formulations, include some breakfast cereals, packaged breads and instant soups. The source material said many contain sweeteners, coloring agents and ingredients rarely used in home cooking, and are designed for convenience, appeal and shelf life.

The study also tested whether reward-system activity might account for part of the association between ultra-processed intake and later body composition. After researchers adjusted for dorsal striatum responses, the association with body mass index was 31% weaker, and the association with body-fat percentage was 44% weaker.

"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 study cannot show that ultra-processed foods directly changed children’s brain activity or were responsible for weight gain.

The findings apply most directly to healthy-weight children ages 7 to 10 similar to those enrolled in BrainChild. They should not be read as evidence about infants, adolescents, adults or children with different health profiles.

Funding came from an American Diabetes Association Pathway Accelerator Award, the National Institute of Diabetes and Digestive and Kidney Diseases of the National Institutes of Health, and NIH support for the REDCap database. The researchers said the BrainChild study will continue following participants through puberty and into early adulthood.

Source: peer-reviewed study, JAMA Network Open; ScienceDaily and Keck School of Medicine of USC, Nov. 3-4, 2026.

Atlas360 reports health research and does not provide medical advice.