Ultraprocessed food linked to stronger reward responses in children’s brains

A small study suggests children who eat more ultraprocessed food may respond more strongly to appetising food cues, potentially helping explain later weight gain.

Researchers say children who eat more ultraprocessed food may show a different brain response to appetising food, a pattern that could help explain why these diets are linked with later weight gain. In a small study of 46 children aged seven to ten, all of whom were at a healthy weight at the start, scientists tracked diet, body fat and later brain activity before following the group for a year. The findings, reported in JAMA Network Open and highlighted by the Keck School of Medicine of USC, suggest that children with higher habitual intake of ultraprocessed foods showed stronger responses in a reward-related brain region when they viewed food images.

The work adds to a growing body of research suggesting that heavily processed foods may influence more than calorie intake alone. A separate randomised crossover study published in Nature Metabolism found that ultraprocessed meals, even when matched closely for nutrients, triggered greater insulin and energy responses than minimally processed meals and were linked to altered brain responses tied to food cues. Together, the studies point to the possibility that processing itself may shape how the body and brain react to eating, not just the amount of fat, sugar or salt in a diet.

Other recent research has raised similar concerns about children’s developing brains. Scientists at Children’s Hospital Los Angeles reported that higher ultraprocessed food intake in early childhood was associated with smaller volumes in several subcortical brain regions by age six, including areas involved in reward, emotion and motivation. The team found that a 10% increase in cumulative intake was linked with nearly a 2% reduction in the volume of those structures, according to the hospital’s summary of the study published in the American Journal of Clinical Nutrition.

Taken together, the findings do not prove that ultraprocessed foods directly cause weight gain or brain changes in every child, but they do strengthen concerns about long-term exposure during early development. The JAMA Network Open study found that the children with stronger reward-related brain responses were also more likely to have higher body-mass index and body fat a year later, which may help explain why some children are more vulnerable to overeating and weight gain than others. Researchers say larger studies will be needed to confirm the pattern and to separate cause from effect.