In Brief
- Children consuming more ultra-processed foods showed higher dorsal striatum activity when viewing tempting food images.
- Heightened reward responses significantly predicted increased BMI and body fat one year later.
- Dorsal striatum activity mediated 31% of the BMI increase and 44% of the body fat gain linked to UPFs.
- Findings highlight how dietary habits alter neural pathways during middle childhood before long-term habits solidify.
Ultra-Processed Foods May Alter Children's Brain Reward Systems to Drive Weight Gain
A study led by researchers at the Keck School of Medicine of USC has uncovered a potential neurobiological explanation for the link between ultra-processed food (UPF) consumption and childhood obesity. The research demonstrates that diets heavy in UPFs are associated with elevated sensitivity in the brain’s reward circuit, which subsequently predicts increased body fat accumulation over time.
Published in JAMA Network Open, the investigation followed 46 children aged 7 to 10 from the ongoing long-term BrainChild study, all of whom initially presented with healthy baseline weights.
Neural Cue Reactivity in the Dorsal Striatum
To evaluate how dietary habits interface with neural development, scientists assessed the children's daily caloric intake, finding that ultra-processed items—such as packaged snacks, sugary cereals, and fast food—accounted for approximately two-thirds of their daily energy consumption on average.
While undergoing functional Magnetic Resonance Imaging (fMRI), participants were shown images of high-calorie food items like cookies, ice cream, and French fries alongside non-food control images. Children with higher UPF diets exhibited pronounced, heightened activation within the dorsal striatum, a brain region integral to processing reward, motivation, and habit formation.
Explaining the Path to Childhood Adiposity
Follow-up examinations conducted one year later revealed that children who demonstrated stronger dorsal striatum activation experienced accelerated physical changes, recording sharper increases in overall body fat percentage, waist circumference, and BMI.
Statistical mediation modeling showed that dorsal striatum activity explained 31% of the relationship between UPF intake and BMI gain, and 44% of the link between UPF consumption and body fat gain.
"This study goes beyond just understanding that UPFs affect weight gain," noted senior author Dr. Kathleen Page, co-chief of the Division of Endocrinology and Diabetes at the Keck School of Medicine of USC. "It actually gives us insight into the neurobiological underpinnings by which these foods may be linked to body composition over time." The research team plans to continue tracking participants through adolescence to observe long-term neural and metabolic trajectories.
