A picture of cookies or French fries can be pretty tempting, especially when you're hungry. But could the foods children regularly eat influence how their brains respond to those images?
New research suggests there may be a connection. In a study of 46 children, those who ate more ultraprocessed foods showed stronger activity in a part of the brain involved in motivation and reward when looking at pictures of appealing foods. Stronger responses were also linked to greater increases in body fat over the following year.
The findings, published in JAMA Network Open, offer an early look at how eating habits and responses to food may be connected during childhood. However, the study was small and observational, so it doesn't prove that ultraprocessed foods changed the children's brains or caused weight gain.
Researchers at the University of Southern California studied children ages 7 to 10 who were at a healthy weight when the research began. They collected information about what the children typically ate and used brain scans to see how they responded to pictures of foods such as cookies and French fries.
On average, nearly 68% of the children's daily calories came from ultraprocessed foods, a broad category that includes many packaged snacks, breakfast cereals, sweetened drinks and convenience foods.
Children who ate more of these foods showed stronger responses to the food pictures in a part of the brain involved in reward and motivation.
About a year later, researchers measured the children's weight and body fat again. Those with stronger brain responses had experienced greater increases in body mass index (BMI) and body fat percentage.
Higher ultraprocessed food intake was also linked to a greater increase in waist circumference. However, the direct connections between these foods and changes in BMI or body fat percentage were less convincing.
That suggests brain responses could be part of the picture, but researchers don't yet know whether they help explain why some children gain more body fat than others.
Another finding raises an important question about what might be driving the relationship.
When researchers accounted for added sugar in the children's diets, the connection between ultraprocessed food intake and brain activity was no longer statistically significant.
That doesn't mean added sugar caused the differences. Instead, it highlights how difficult it can be to separate the effects of food processing from the nutritional characteristics of the foods themselves.
After all, ultraprocessed foods aren't nutritionally identical. Some contain substantial amounts of added sugar, saturated fat or sodium, while others provide fiber, protein and important nutrients. This study couldn't identify which foods or ingredients might explain the findings.
There are other limitations. The researchers estimated the children's diets using just two days of reported food intake, and brain activity was measured only once. They also didn't test whether the children actually wanted or ate more food after seeing the pictures.
It's possible that children who naturally respond more strongly to appealing foods are also more likely to choose certain products, rather than those foods causing the differences in brain activity.
And because the children were still growing, increases in weight and body size aren't necessarily signs of a health problem.
The researchers hope to investigate whether changing children's diets affects how their brains respond to food. For now, the findings raise interesting questions about the relationship between what children eat, what catches their attention and how their bodies change as they grow.
The research was supported by the American Diabetes Association and the National Institutes of Health.