Ultra-Processed Foods Linked to Heightened Brain Reward Response and Later Weight Gain in Children

Key Takeaways: 

• Children who ate larger amounts of ultra-processed foods showed greater activity in the dorsal striatum, a brain region involved in reward and motivation, when viewing pictures of appealing foods.
  
• Children with stronger responses in this region tended to have greater increases in BMI and body fat percentage over the following year, even though every participant had a healthy weight at the start of the study.
  
• Accounting for this brain response weakened the link between ultra-processed food intake and BMI by 31%, and the link with body fat percentage by 44%, although the observational design means the study cannot show cause and effect.
  
  
  

What ultra-processed foods are and why they matter

Ultra-processed foods (UPFs) include many everyday products, such as breakfast cereals, packaged bread and instant soups. They are manufactured to be appealing, convenient and able to stay fresh for extended periods. Many contain artificial sweeteners, colouring agents and other ingredients that are rarely used in home cooking.

These products make up a substantial portion of children’s diets. In the United States, they account for approximately 67% of the calories children consume.

Previous research has associated ultra-processed food consumption with obesity, type 2 diabetes and cardiovascular disease. However, scientists are still trying to understand the biological processes that might explain these connections. The new investigation, supported in part by the National Institutes of Health, combined magnetic resonance imaging (MRI), dietary assessments and measurements of children’s body composition to explore whether the brain’s response to food could play a role.

Why researchers focused on childhood

The study’s senior author is Kathleen A. Page, MD, professor of medicine and paediatrics and co-chief of the Division of Endocrinology and Diabetes at the Keck School of Medicine of USC. She explained why this stage of life is so significant.

“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,” said Page. “We’re particularly interested in understanding these processes in children, because we believe that intervening early could make a real difference.”

How the study was carried out

The research team studied 46 children between the ages of seven and 10 who were enrolled in the ongoing BrainChild study, which examines factors contributing to diabetes and obesity. Every participant had a healthy weight when the research began, giving scientists an opportunity to look for potential warning signs before excess weight developed.

At the start of the study, the children underwent brain scans while looking at pictures of appealing foods, such as cookies or French fries. Researchers also gathered information about the children’s diets and recorded several health measurements, including body mass index (BMI), body fat percentage and waist circumference. After one year, the team took these physical measurements again to identify any changes.

Brain scans reveal a link to future weight gain

The brain scans revealed a notable pattern. Children who consumed larger amounts of ultra-processed foods showed greater activity in the dorsal striatum when viewing the food pictures. This part of the brain helps regulate reward and motivation, which makes it particularly relevant to how people respond to desirable foods.

Importantly, children with stronger responses in this brain region also tended to experience greater increases in BMI and body fat percentage over the next year. The findings suggest that heightened sensitivity to food cues may be one factor connecting ultra-processed diets with subsequent weight gain.

How brain reward activity may influence body fat

By the end of the study, children who consumed more ultra-processed foods generally had a higher BMI, a greater body fat percentage and a larger waist circumference.

The researchers then examined whether differences in brain activity could help account for these associations. When they adjusted their analysis to take the children’s dorsal striatum responses into account, the relationship between ultra-processed food intake and BMI became 31% weaker. The corresponding association with body fat percentage decreased by 44%.

These reductions suggest that the brain’s reward response may help explain part of the relationship between ultra-processed food consumption and changes in body composition. Although the results do not demonstrate that these foods directly alter brain function, they offer a possible biological explanation for an association that has been observed in previous research.

“This study goes beyond just understanding that UPFs affect weight gain,” Page said. “It actually gives us insight into the neurobiological underpinnings by which these foods may be linked to body composition over time.”

Making healthier foods more accessible

The researchers caution that improving children’s diets cannot depend entirely on individual families. Ultra-processed products are often inexpensive, widely available and easy to prepare, making them practical choices for households facing financial or time constraints.

“Changing the food environment to help people access healthier, more minimally processed foods is an important part of the solution,” Page said.

For healthcare professionals who work with children and families, findings like these highlight the range of influences on weight in childhood – from biology to the wider food environment. Those wishing to build their knowledge in this area may find the College of Contemporary Health’s Childhood Obesity Essentials CPD short course a useful starting point.

Limitations of the research

There are important limitations to consider. Because the study was observational, it cannot determine whether eating ultra-processed foods directly causes heightened brain activity or increases in body weight. The findings establish relationships between these factors, but additional research is needed to determine whether one causes another.

What comes next

Page hopes to address the question of causation in a future intervention study. The proposed research would provide children who regularly consume ultra-processed foods with more minimally processed alternatives. Scientists could then examine whether changing the children’s diets affects how their brains respond to food images, and whether any differences are associated with reduced weight gain.

Meanwhile, the BrainChild study will continue tracking participants as they move through puberty and into early adulthood. By monitoring brain development, body composition, dietary patterns and general health over time, researchers hope to gain a clearer picture of how childhood nutrition may influence long-term health.

CCH insight

This research adds to the evidence that weight gain in childhood is shaped by far more than individual choices. If you support children and families in your practice, our Childhood Obesity Essentials CPD short course can help you deepen your understanding of this area. Explore the course on the College of Contemporary Health website.

Explore Childhood Obesity Essentials →

Source: JAMA Network Open