Ultraprocessed foods may prime children’s brains for later weight gain

Children who ate more ultraprocessed foods showed stronger reward-system responses to food images, which were linked to increased body fat one year later, a study suggests.

Children who eat a larger share of ultraprocessed foods may show a stronger brain response to tempting food images, and that heightened sensitivity could be tied to gains in body fat over the following year, according to a new study published in JAMA Network Open.

The research adds to a growing body of evidence suggesting that heavily processed foods may influence more than weight alone. In earlier work reported by Children’s Hospital Los Angeles and Powers Health, higher consumption of ultraprocessed foods in early childhood was associated with differences in brain structure by age six, particularly in regions involved in reward, emotion and motivation. That research did not find a measurable link with cognitive performance, indicating that brain changes may emerge before any detectable effect on memory or thinking.

In the new study, researchers examined 46 children aged seven to ten who were already at a healthy weight at the start of the BrainChild study, which follows children at risk for diabetes and obesity. The team used MRI scans to observe brain activity while the children looked at images of highly appealing foods, then compared those responses with diet records and measures of body composition taken at the beginning of the study and again one year later.

According to the findings, children who consumed more ultraprocessed foods showed stronger activation in the dorsal striatum, a part of the brain associated with reward and motivation, when exposed to food cues. Those sharper responses were also linked to higher body mass index and greater body fat a year later. When the researchers took the brain response into account, the relationship between ultraprocessed food intake and later body fat weakened, suggesting the reward system may help explain part of the connection.

Kathleen Page, the senior author and a professor of medicine and paediatrics at the Keck School of Medicine of the University of Southern California, said the finding matters because childhood is a period when both the brain and eating habits are still taking shape. She said the team wants to understand how food environments shape those processes early, when intervention may have the greatest effect.

The study does not prove that ultraprocessed foods directly alter the brain or cause weight gain, only that the two appear to move together over time. But the results fit with other recent research pointing to possible biological pathways. A separate Nature Metabolism study found that ultraprocessed meals could trigger different insulin and brain responses even when compared with nutritionally matched whole foods, while a JAMA Pediatrics paper suggested that having more ultraprocessed foods at home may heighten children’s attention towards those products.

Page said the broader lesson is not simply that families should try harder to avoid these foods, since they are often the cheapest, most convenient and most widely available option. She argued that healthier choices have to be easier to reach if children are to have a fairer food environment. The BrainChild project will continue to follow participants through puberty and into young adulthood, and Page hopes to test whether replacing ultraprocessed foods with less processed alternatives changes brain responses and slows weight gain.