Children’s Brain Reward System May Help Explain Weight Gain Linked to Ultra-Processed Foods

 Children’s Brain Reward System May Help Explain Weight Gain Linked to Ultra-Processed Foods

Researchers found that children who consumed more ultra-processed foods tended to show stronger activity in a brain region involved in reward and motivation when they looked at pictures of appealing foods.

The findings, published in JAMA Network Open, suggest that the brain's response to food cues could be one factor helping explain why higher consumption of ultra-processed foods is associated with increases in body fat during childhood. However, researchers stress that the study does not prove that ultra-processed foods directly cause changes in the brain or weight gain.

What Are Ultra-Processed Foods?

Ultra-processed foods, often called UPFs, are industrially manufactured products designed to be convenient, long-lasting and highly appealing.

Examples can include some packaged breakfast cereals, packaged breads, instant soups and other ready-to-eat products. These foods may contain ingredients that are not commonly used in traditional home cooking, including certain sweeteners, colours and other additives.

. According to the researchers, around 67% of daily calories consumed by US children come from ultra-processed foods, highlighting how significant these products are in children's diets.

How the Study Examined Children's Brains

Researchers from the Keck School of Medicine of USC studied 46 children between seven and 10 years old who were part of the long-term BrainChild study.

Importantly, the children began the study at a healthy weight. This allowed researchers to examine whether dietary patterns and brain responses were associated with changes in body composition over time rather than simply comparing children who were already overweight with those who were not.

At the beginning of the study, researchers collected information about the children's diets, BMI, body-fat percentage and waist circumference. The children also underwent MRI brain scans while looking at pictures of highly appetising foods, including foods such as cookies and French fries. Researchers repeated measurements of body composition one year later.

Brain Reward Response Was Linked to UPF Intake

One of the most interesting findings involved the dorsal striatum, a brain region associated with reward, motivation and responses to rewarding experiences.

Children who reported eating more ultra-processed foods showed stronger responses in this area when viewing images of appetising foods.

The researchers also found that stronger dorsal striatum responses were associated with higher BMI and body-fat percentage one year later. This raises the possibility that frequent exposure to highly palatable foods may be connected with stronger food-cue responses, although more research is needed to understand exactly how the relationship works.

Brain Activity May Explain Part of the Association

The researchers performed additional analyses to determine whether differences in children's brain responses could help explain the relationship between ultra-processed food consumption and later changes in body composition.

When the researchers accounted for differences in dorsal striatum responses, the associations between ultra-processed food intake and later BMI and body-fat percentage became weaker by approximately 31% and 44%, respectively.

These findings suggest that reward-related brain responses may play a role in the relationship between UPF consumption and childhood adiposity. They do not, however, demonstrate that eating ultra-processed foods permanently changes the brain.

Why Childhood May Be an Important Period

Childhood is a particularly important period for studying eating behaviour because the brain is still developing and food preferences are being established.

Researchers say children may be especially sensitive to their food environment. Regular exposure to highly appealing foods could potentially influence eating preferences and responses to food cues over time.

Kathleen A. Page, MD, the study's senior author, emphasised that understanding these processes during childhood could help researchers identify opportunities for earlier intervention.

Parents Should Not Carry All the Responsibility

The researchers also highlighted an important issue: changing children's diets is not simply a matter of telling families to make better choices.

Ultra-processed foods are often affordable, convenient and widely available. For busy families, they can be easier to purchase and prepare than fresh or minimally processed alternatives.

This means improving children's diets may require changes in the wider food environment, including better access to nutritious, minimally processed foods.

What Parents Can Do

Instead, families can gradually make minimally processed foods a larger part of everyday meals.

Useful choices can include:

Fresh or frozen vegetables

Whole fruits

Beans and lentils

Eggs

Plain yoghurt

Nuts and seeds

Whole grains

Fish and poultry

Homemade soups and meals

Replacing some highly processed snacks with fruit, yoghurt, nuts or other minimally processed options can be a practical starting point.

More Research Is Needed
Researchers measured children's food intake, brain responses and body composition but did not randomly assign children to different diets.

As a result, the findings cannot establish cause and effect. Other factors could contribute to both children's food choices and their brain responses.

The researchers are planning intervention research in which children who regularly consume ultra-processed foods would receive more minimally processed foods. Researchers could then determine whether changes in diet lead to changes in brain responses and subsequent weight gain.

A New Clue in the Childhood Obesity Puzzle

The research adds an important piece to the growing scientific discussion about ultra-processed foods and childhood obesity.

Rather than looking only at calories or body weight, the study suggests that the brain's reward system may also be involved. Understanding how food cues, eating habits and brain development interact could eventually help scientists develop better strategies for preventing unhealthy weight gain.

For now, the message is not that every ultra-processed food is harmful or that parents should eliminate packaged foods entirely. Instead, the research supports a broader focus on creating food environments where nutritious, minimally processed foods are easier and more accessible choices for children.