Ultra-processed foods, often abbreviated as UPFs, are industrial formulations such as breakfast cereals, packaged breads and instant soups. They are designed to be highly palatable, convenient and shelf-stable, and they frequently contain artificial sweeteners, colors and other ingredients that people do not typically use when cooking at home. In the United States, children obtain roughly 67 percent of their daily calories from these products on average. Previous research has linked high UPF consumption to weight gain, type 2 diabetes and cardiovascular disease, but the neural mechanisms that might contribute to those risks have remained poorly understood, particularly in children.

The new study was designed to help fill that gap. Funded in part by the National Institutes of Health, the research team collected magnetic resonance imaging brain scans, detailed dietary information and measurements of body composition in a group of children enrolled in the long-term BrainChild study of diabetes and obesity risk. The analysis included 46 children between the ages of seven and ten, all of whom started the study at a healthy weight. That design choice allowed the investigators to focus on the early risks of ultra-processed foods, before excess weight had already developed.

At the start of the study, each child underwent an MRI scan while viewing photographs of highly appetizing foods, such as cookies or French fries. The researchers also recorded each child’s diet, body mass index, body fat percentage and waist circumference. One year later, they repeated the body composition measurements, tracking BMI, body fat percentage and waist circumference over that interval. This combination of neuroimaging and longitudinal anthropometric data made it possible to ask whether brain responses to food cues were associated with subsequent changes in adiposity, not merely differences in weight at a single point in time.

The central result concerned the dorsal striatum, a brain region involved in reward and motivation. Children who consumed more ultra-processed foods showed stronger responses to the appetizing food images in this region. Stronger dorsal striatum responses, in turn, were associated with greater increases in BMI and body fat percentage one year later. In other words, the same neural signal that tracked UPF intake also tracked subsequent fat gain, placing the dorsal striatum on the pathway between diet and body composition in this observational data.

Consistent with that pattern, children who ate more ultra-processed foods had greater waist circumference, BMI and body fat percentage at the end of the study year. When the researchers statistically accounted for differences in dorsal striatum responses to food images, the associations between UPF consumption and BMI weakened by 31 percent, and the associations with body fat percentage weakened by 44 percent. Those attenuations suggest that differences in brain responses to food cues may help explain, at least in part, the link between ultra-processed food consumption and weight gain in children, although the observational design means causality cannot be established from these data alone.

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, emphasized why childhood is a critical window for this kind of research. “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,” Page said. “We’re particularly interested in understanding these processes in children, because we believe that intervening early could make a real difference.”

Page added that the study’s contribution goes beyond confirming that ultra-processed foods are associated with weight gain. “This study goes beyond just understanding that UPFs affect weight gain,” she said. “It actually gives us insight into the neurobiological underpinnings by which these foods may be linked to body composition over time.” The dorsal striatum is a component of the brain’s reward network, and the new findings indicate that children whose diets contain more of these engineered, highly palatable products also show more vigorous reward-region responses to the sight of appetizing foods, and that this neural signal statistically accounts for a meaningful share of the association between UPF intake and later gains in BMI and body fat.

The researchers are careful to note the limits of what an observational study can show. Because the children were not randomly assigned to different diets, the study cannot establish whether ultra-processed food consumption causes changes in brain activity or weight gain. Reverse pathways remain possible, as do confounding factors that influence both diet and brain function. To test cause and effect directly, Page aims to conduct an intervention study in which children who regularly eat ultra-processed foods are given more minimally processed foods. Researchers could then track whether their brain responses to food images change over time and whether those changes are associated with less weight gain, providing a stronger test of the relationship suggested by the current data.

The team also stresses that responsibility for dietary change should not fall solely on families and children, since ultra-processed products are often the most accessible, affordable and convenient options available. “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 to follow the children through puberty into young adulthood, documenting brain changes, body composition and links between diet and overall health. The study’s authors, in addition to Page, are Jasmin M. Alves, Ella Morgan, Brendan Angelo, Kianna Le and Jared Smith of the Division of Endocrinology and Diabetes, Department of Medicine and the Diabetes and Obesity Research Institute at the Keck School of Medicine of USC; Kay Jann of the USC Stevens Neuroimaging and Informatics Institute; and Ting Chow and Anny H. Xiang of the Department of Research and Evaluation at Kaiser Permanente Southern California in Pasadena, California. The work was supported by an American Diabetes Association Pathway Accelerator Award and by the National Institute of Diabetes and Digestive and Kidney Diseases of the National Institutes of Health, with additional support for the REDCap database from the Southern California Clinical and Translational Science Institute, and the authors reported no conflicts of interest.

Subject of Research: Neural reward responses to food cues linking ultra-processed food intake and adiposity gain in children

Article Title: Children who eat more ultra-processed foods show stronger brain responses to appetizing foods

Article References: Children who eat more ultra-processed foods show stronger brain responses to appetizing foods. Original publication (Bibliographic details unavailable.)

Image Credits: AI Generated

DOI: Not provided

Keywords: ultra-processed foods, children, brain imaging, dorsal striatum, reward network, obesity, body fat, MRI, nutrition, JAMA Network Open, BrainChild study, pediatric health