Children who are overweight or obese are more susceptible to persuasive junk food advertisement on television when compared to their normal weight peers, says a new study.

Food companies spend a staggering $10 billion to market their food to children. About 98 percent of all foods that are advertised to children on TV are high in fat, sugar or sodium, says the study.

Past research has co-related TV ads that promote unhealthy food choices and risk of obesity among children. TV viewing itself has been seen as an independent risk factor for weight gain in both adults and children. Almost all studies dealing with obesity and children have called for better regulation of food-advertisements on TV channels.

Advertisement of unhealthy food on television channels is not just restricted to the U.S. Another related study that involved 13 research groups in 11 countries also found that "children were exposed to high volumes of television advertising for unhealthy foods, featuring child-oriented persuasive techniques."

In the current study, researchers assessed how the brain activity of overweight children changes when exposed to advertisement of junk food.

"This study provides preliminary evidence that obese children may be more vulnerable to the effects of food advertising. One of the keys to improving health-related decision-making may be found in the ability to improve self-control," noted Amanda S. Bruce from University of Missouri-Kansas City.

The small study included ten normal-weight children and ten children who were overweight. Children between the ages of 10 and 14 were shown 60 logos each of companies that manufacture junk food and other non-food making companies. The children were also hooked on to MRI scanners that detected the amount of activity going on in certain brain regions.

"We were interested in how brain responses to food logos would differ between obese and healthy weight children," said Bruce.

Researchers found that brains of children who were obese or overweight showed higher activity in the "reward region" of the brain while in healthy kids, high activity was seen in self-control. Researchers say that the brains of overweight and healthy-weight kids differ in the way they respond to food advertisements.