The kids in the MRI scanner saw pictures of cookies and fries. Those who ate more ultra-processed foods in their usual diets showed a stronger response in a brain region involved in reward and motivation. A year later, children with stronger responses tended to see bigger increases in body fat percentage, according to the USC-led study in JAMA Network Open.
The study, highlighted by ScienceDaily, offers a clue about why researchers are looking beyond what children eat to how they respond to the sight of food. The study followed just 46 children, ages 7 to 10, who started at a healthy weight. It was observational, so it leaves cause and effect unresolved.
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Where the Signal Showed Up
Researchers compared brain activity when children looked at food photos with activity when they looked at pictures of nonfood objects. The difference associated with eating more ultra-processed foods showed up in the dorsal striatum. The team found no clear association in the ventral striatum, another region it examined. Across the group, ultra-processed foods accounted for about two-thirds of daily calories, according to the published study.
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What Changed a Year Later
The children with stronger responses also tended to have larger increases in BMI. When researchers accounted for the scan results, the link between ultra-processed food intake and changes in body fat percentage weakened. “These findings give us a better understanding of a potential pathway linking ultraprocessed food consumption with changes in body fat during childhood,” study co-senior author Anny H. Xiang, PhD, MS, told Kaiser Permanente’s research newsroom.
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The Next Test for Researchers
The team scanned each child at one point in time. Study co-senior author Kathleen A. Page, MD, wants to test whether giving children more minimally processed foods changes how their brains respond to food pictures. “Changing the food environment to help people access healthier, more minimally processed foods is an important part of the solution,” Page told USC’s Keck School of Medicine.
The practical takeaway is to look at the foods kids can reach for day after day. The scans give researchers a way to test how those everyday choices and children’s responses to food might be connected.
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This story was originally published by Men’s Journal on Nov 5, 2026, where it first appeared in the Health section. Add Men’s Journal as a Preferred Source by clicking here.
