Kids Who Eat More Ultra-Processed Foods Show Stronger Brain Reward Signals: Study

Could ultra-processed foods be influencing children's brains in ways that encourage weight gain? A new study suggests that children who consume more ultra-processed foods show stronger activity in brain regions involved in food reward, which may be linked to increased body fat over time.

Published in JAMA Network Open, the study conducted by researchers at the Keck School of Medicine of the University of Southern California investigated how ultra-processed food consumption influences brain responses to food and subsequent changes in body composition.

Ultra-processed foods include products such as packaged snacks, breakfast cereals, instant soups and other highly processed foods containing additives and ingredients rarely used in home cooking.

Researchers examined 46 children aged seven to 10 years who had a healthy body weight at the beginning of the study.

Participants underwent functional magnetic resonance imaging (fMRI) scans while viewing pictures of appealing foods, including cookies and French fries.

Researchers also assessed dietary intake, body mass index (BMI), body fat percentage and waist circumference, repeating the physical measurements after one year.

The findings revealed that children consuming higher amounts of ultra-processed foods showed greater activity in the dorsal striatum, a brain region involved in reward processing and motivation.

Importantly, stronger activity in this brain region was associated with greater increases in BMI and body fat percentage over the following year.

Researchers also found that accounting for dorsal striatum activity weakened the association between ultra-processed food consumption and BMI by 31%, while the association with body fat percentage decreased by 44%.

However, the study involved only 46 children and was observational, meaning it could not establish that ultra-processed foods directly alter brain function or cause obesity.

The findings highlight the potential importance of childhood dietary habits in brain reward responses and weight regulation, while emphasising the need for larger intervention studies to confirm these relationships.

REFERENCE: Jasmin M. Alves, et al.; Ultraprocessed Food Intake, Striatal Response to Food Cues, and Adiposity Gain in Children. JAMA Network Open, 2026; 9 (10): e2640252 DOI: 10.1001/jamanetworkopen.2026.40252