Does Childhood Obesity Start in the Brain?

Why are some people obese when others are not? Understanding what triggers weight gain, especially in children, could help resolve one of biggest public health challenges of our time. The percentage of children with obesity has tripled since the 1970s, according to CDC, and today 1 in 5 school-age children is obese, putting them at risk for a lifetime of chronic disease.

Children with overweight parents are more likely to become overweight, but that’s not the whole story. To understand why some children become overweight and others do not, researchers at the Institute for the Developing Mind at Children’s Hospital, Los Angeles, used functional magnetic resonance imaging (fMRI) to watch how children’s brains responded when stimulated by food.

Food activates the brain for just about everyone. What makes the difference, the team found, is whether the brain’s centers that support self-regulation and attention are also activated when food is around, because these signals help children avoid over-eating.

The study involved 36 teenagers between the ages of 14 to 19 years. Of the group, 10 were overweight or obese, 16 were lean but at risk because their mothers were overweight, and 10 were lean and at low risk, because their mothers were also lean. The teens underwent brain scans with fMRI, and viewed words that described high-fat foods, low-fat foods, and non-food items. After each word, the teens had to describe their appetite. Afterward, they all ate at a buffet with a variety of food choices—both low- and high-calorie.

Reward circuits in the brain showed activity for all food-related words. But there was a difference for teens who were obese but lean and at-risk: food-related words brought less activity in the self-regulation areas of the brain, while teens who were lean and at low risk had more activity in the self-regulation areas. And when the buffet was served, the obese teens ate the most, followed by the lean but at-risk children, and the lean children with lean mothers ate the least.

“This study establishes that the risk for obesity isn’t driven exclusively by the absence or presence of urges to eat high-calorie foods, but also, and perhaps more importantly, by the ability to control those urges,” lead investigator Bradley Peterson, MD, the Institute’s director, said in a statement. “These findings suggest that interventions designed to stimulate the self-regulatory system in adolescents may provide a new approach to treating and preventing obesity.”

Findings will appear in the October issue of the journal Neurolmage.

Reference

Carnell S, Benson L, Chang KY, et al. Neural correlates of familial obesity risk and overweight in adolescence. Neurolmage. 2017; 159:236-247. https://doi.org/10.1016/j.neuroimage.2017.07.052.