Children with a genetic risk for obesity respond more strongly to fast food television advertising in a brain region associated with reward processing, according to a new study out Monday that may help understand why some children are more likely to overeat unhealthy foods.

The study is the first-of-its kind to examine how a key obesity gene, known as the fat-mass and obesity-associated (FTO) gene, influences brain response to food advertisements and other cues to eat, according to researchers at the Dartmouth College.

The findings were published in the U.S. journal Proceedings of the National Academy of Sciences.

In the study, 78 children, aged nine to 12 years old, watched a children's television show in an magnetic resonance imaging scanner.

To simulate the experience of watching television from home, the show included 12 minutes of commercial breaks -- half were advertisements for fast food and the other half for non-food items.

Children were also evaluated on their genetic risk for obesity based on the FTO gene, which strongly predicts obesity across the lifespan.

The nucleus accumbens, a region in the brain commonly associated with reward craving, was not only physically larger in children with the obesity-risk FTO genotype compared to genetically low-risk children but also showed a stronger craving response to the food commercials.

"About one-third of commercials children see on network television are food advertisements, and each one is a prompt to eat," senior author Diane Gilbert-Diamond, assistant professor of Epidemiology at Dartmouth's Geisel School of Medicine, said in a statement.

"We know from our prior work that children with this same genetic obesity risk factor are more likely to overeat after watching food advertisements on TV, even when they are not hungry. The brain scans suggest that these children may be especially vulnerable to food cues, and that limiting food advertisement exposure could be an effective way to combat child obesity."