Researchers looked at frequency magnetic resonance imaging (fMRI) images to compare neural responses to food cues in overweight and normal weight adolescents.
They noted that food stimuli activated regions of the brain associated with reward and emotion in all groups but overweight adolescents had progressively less neural activity in circuits of the brain that support self-regulation and attention.
Of the 36 adolescents (ages 14 to 19 years) enrolled in the study published in Neuroimage, 10 were overweight/obese, 16 were lean but considered at high risk for obesity because they had overweight/obese mothers and 10 were lean/low risk since they had lean mothers. The adolescents underwent brain scanning using fMRI, while they viewed words that described high-fat foods, low-fat foods and non-food items. Then they rated their appetite in response to each word stimulus. Following the activity, all participants were offered a buffet that included low- and high-calorie foods -- to relate participants test responses to real-world behavior.
The investigators observed that after viewing food-related words, brain circuits that support reward and emotion were stimulated in all participants. In adolescents who were obese or who were lean but at high familial risk for obesity, they observed less activation in attention and self-regulation circuits.
Brain circuits that support attention and self-regulation showed the greatest activation in lean/low-risk adolescents, less activity in lean/high-risk participants and least activation in the overweight/obese group. Also, real world relevance mirrored fMRI findings -- food intake at the buffet was greatest in the overweight/obese participants, followed by the lean/high-risk adolescents and lowest in the lean/low-risk group.