FIU study finds brain differences linked to obesity risk in preschoolers

MIAMI, Sept. 22, 2026 /PRNewswire/ -- Children as young as 4 with a higher body mass index (BMI) showed differences in several brain regions involved in reward, taste and hunger, according to a new study from Florida International University. The findings suggest the relationship between obesity risk and the developing brain may begin years earlier than scientists previously realized. 

Published in the Nature Portfolio journal Scientific Reports, the study is one of the first to use an advanced MRI technique to examine the relationship between obesity risk and brain development in preschool-aged children. 

Childhood obesity is a growing public health concern and has been linked to a range of health problems, including diabetes, heart disease and mental health challenges. Yet researchers still know relatively little about when the relationship between body weight and the brain begins.  

"Most prevention efforts begin only after a child is already showing signs of weight gain," said Anthony Dick, professor of developmental science and cognitive neuroscience at FIU and one of the study's senior authors. "If we can better understand when these brain-body relationships first appear, we may eventually be able to identify obesity risk earlier and develop interventions before unhealthy patterns become established." 

Researchers at FIU's Center for Children and Families scanned the brains of 159 children ages 4 to 7, including 81 with ADHD and 78 without, using an advanced MRI technique called Restriction Spectrum Imaging (RSI). They compared the scans with several measures of body size, including BMI, waist circumference and body fat percentage. 

Of all the measures the researchers evaluated, only BMI was associated with differences in the brain. 

Children with a higher BMI showed differences in brain regions involved in reward, motivation, taste and craving. Researchers also found a small signal in the hypothalamus, which helps regulate hunger, though they say that finding needs to be confirmed with follow-up research. 

"Previous studies have identified similar patterns in adolescents," said Mohammadreza (Masood) Bayat, the study's lead author and a cognitive neuroscience doctoral student at FIU. "Our findings push that timeline back by several years, making it one of the earliest investigations of how body weight and brain development may be connected. We're not saying these brain differences are causing higher body weight, or that higher body weight is causing brain differences. This study only tells us they're connected." 

One of the study's most novel findings involved the insula, a brain region that had not emerged in similar studies of older children. 

The researchers also expected children with ADHD to show a stronger correlation between brain changes and BMI, since ADHD has been linked to many of the same brain circuits involved in reward and to behaviors like impulsivity. Instead, children with and without ADHD showed the same overall pattern as children without ADHD. 

"We honestly expected ADHD to play a bigger role," said Paulo Graziano, professor of psychology and one of the study's authors. "Instead, the pattern was consistent across both groups. That tells us these associations may reflect something broader about early brain development rather than ADHD specifically." 

The researchers note that the study captured only one point in time, so it cannot determine whether the brain differences came before changes in body weight, resulted from them or influenced one another over time. They emphasize the findings are not a reason for parents to change how they approach their child's nutrition or physical activity. Rather, the study is an early step toward understanding when body weight and brain development first become connected. 

Next, the team plans to continue following children over time to see whether brain differences show up before or after changes in body weight. Future studies will also pair brain imaging with direct measures of metabolism and inflammation to better understand what's driving these early differences. 

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SOURCE Florida International University