In a small group of children, the pull of a cookie picture seems to echo into the body over time. Forty-six seven- to ten-year-olds, all starting at a healthy weight, were scanned while viewing tempting food images, and those who ate more manufactured, highly palatable products showed a stronger reward response in the brain's motivation circuitry. A year later, that same response tracked with gains in body fat. It is a partial thread rather than a full explanation, and it arrives at a moment when families, food systems and young brains are all still shaping habits that may last a lifetime.
Children's Brain Reward Responses May Help Explain Ultra-Processed Food Links to Weight Gain
The brain may become more sensitive to food cues as children eat more UPFs
Mark
What's the core finding here?
Mimi
Kids who ate more ultra-processed food had stronger reward-region responses to pictures of appetizing food, and those responses tracked with more body fat a year later.
Mark
Which brain region?
Mimi
The dorsal striatum, tied to reward and motivation.
Luke
Before we get carried away, how big is this study?
Mimi
Forty-six children, ages seven to 10, all at a healthy weight when they started.
Luke
That's small, and it's observational. So nobody can say UPFs changed the brains.
Mimi
Right. The authors say so themselves. It can't establish cause for either the brain activity or the weight gain.
Mark
But the 31% and 44% figures seem meaningful.
Mimi
They show how much the BMI and body fat associations weakened once the brain response was accounted for. It points to a partial explanation.
Luke
Partial is the key word. More than half of the body fat link remains unexplained by this measure, and the source doesn't say what else is involved.
Mark
What happens next?
Mimi
Page wants an intervention trial swapping in minimally processed foods, and BrainChild will keep following the children into young adulthood.
The Pulse
- Forty-six young children lay in MRI scanners and reacted to images of cookies and fries, revealing a brain signal that may be tugging at them before they ever take a bite.
- Children who ate more ultra-processed food lit up more strongly in the dorsal striatum, the reward center, setting off alarm bells for researchers tracking early weight gain.
- Accounting for that brain response weakened the link between ultra-processed eating and body fat by 44%, suggesting a real mechanism but leaving much of the story unexplained.
- The study is observational and small, so researchers are preparing an intervention trial that will swap in minimally processed foods to see whether brain responses and weight actually shift.
- The long-running BrainChild study will keep tracking these children through puberty into adulthood, with the outcome still open.
In a small group of children, the pull of a cookie picture seems to echo into the body over time. Forty-six seven- to ten-year-olds, all starting at a healthy weight, were scanned while viewing tempting food images, and those who ate more manufactured, highly palatable products showed a stronger reward response in the brain's motivation circuitry. A year later, that same response tracked with gains in body fat. It is a partial thread rather than a full explanation, and it arrives at a moment when families, food systems and young brains are all still shaping habits that may last a lifetime.
Forty-six children, aged seven to ten, sat in an MRI scanner and looked at pictures of foods designed to be irresistible: cookies, French fries. Their brains told a story. The children who ate more ultra-processed foods, the packaged cereals, instant soups and shelf-stable breads that make up a large share of American children's calories, showed stronger activity in the brain's reward network. A year later, that same activity was linked to increases in body fat.
The study comes from the BrainChild project on diabetes and obesity risk, and every child began at a healthy weight. That detail matters, because it lets researchers look at early effects before they become entrenched. Earlier work had connected these products to weight gain, type 2 diabetes and heart disease, but the brain pathway remained a blank. This research helps fill it. When the team accounted for the reward response, the link between ultra-processed eating and body fat weakened by 44%. The brain appears to be part of the mechanism, though not the whole of it.
Senior author Kathleen Page noted that children's brains, habits and tastes are still forming, which is why early intervention may matter so much. The researchers were also clear that the burden should not fall only on children and families, since these foods are often the cheapest and most convenient choice available.
Because the study is observational, it cannot prove cause. Page plans a trial that will give children more minimally processed foods and watch whether their brain responses and weight change in step. BrainChild will continue following these children into young adulthood, watching how the brain, the body and the diet continue to shape one another.
Forty-six children between the ages of seven and 10 lay in an MRI scanner and looked at photographs of foods built to be tempting, such as cookies and French fries. The scans, taken at the start of a long-term study, have now yielded a finding published in JAMA Network Open: the children who ate more ultra-processed food showed stronger activity in the brain's reward network when they viewed those images. That activity was also linked to gains in body fat a year later.
Ultra-processed foods, or UPFs, are manufactured products such as breakfast cereals, packaged bread and instant soups. They are designed to be highly palatable, convenient and shelf-stable, and they often contain artificial sweeteners, colors and other ingredients people don't typically use when cooking at home. U.S. children get about 67% of their daily calories from them, on average.
Earlier research has tied these products to weight gain, type 2 diabetes and cardiovascular disease. What has been less clear is how the brain's reward network might contribute to those risks. The new study, funded in part by the National Institutes of Health, set out to help fill that gap by combining MRI scans, dietary information and measurements of body composition.
The children are part of the BrainChild study of diabetes and obesity risk, and all of them began at a healthy weight, which let the researchers focus on early effects. At the outset, the team scanned each child while they viewed the food photos and gathered data on diet, body mass index (BMI), body fat percentage and waist circumference. A year later, they measured BMI, body fat percentage and waist circumference again.
Children who consumed more UPFs responded more strongly to the food images in the dorsal striatum, a region involved in reward and motivation. Stronger responses there were in turn associated with higher BMI and body fat percentage a year later. By the end of the study, children with higher UPF intake also had greater waist circumference, BMI and body fat percentage. When the researchers adjusted for differences in dorsal striatum response, the associations for BMI and body fat percentage weakened by 31% and 44%, respectively. That suggests the brain response may account for part of the link between UPF consumption and weight gain, though not all of it.
"Children's brains are still developing, habits are still forming and food preferences are still being made," said 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. She said the team is focused on children because early intervention could make a real difference, and that the study offers insight into the neurobiological underpinnings by which these foods may be linked to body composition over time.
The researchers stress that responsibility should not fall only on families and children, since UPFs are often the most accessible, affordable and convenient options. Page said changing the food environment so people can reach healthier, more minimally processed foods is an important part of the solution.
The study is observational, so it cannot show whether UPFs cause the changes in brain activity or the weight gain. Page plans an intervention study in which children who regularly eat UPFs would be given more minimally processed foods, with researchers tracking whether their brain responses to food images shift and whether any shift goes along with less weight gain. BrainChild will also keep following the children through puberty into young adulthood, recording brain changes, body composition and links between diet and health.
Notable Quotes
Changing the food environment to help people access healthier, more minimally processed foods is an important part of the solution.— Kathleen A. Page, MD, Keck School of Medicine of USC
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