Banning fast-food advertising could lead to a decrease in the number of overweight and obese children by as much as 18 percent, according to a new study published this month in the Journal of Law and Economics.

Childhood obesity has become a national problem in the United States. The US Centers for Disease Control and Prevention estimates that the percentage of children ages 6 to 11 more than tripled between 1970 and 1999, as reports show that one out of four children in the US is obese or overweight. Thirty years ago, just one out of seven children had problems with his weight.

Childhood obesity has become a major reason of concern, as most of the obese children are more likely to develop obesity-related diseases. According to the American Diabetes Association, about 176,500 children and adolescents younger than 20 have diabetes, and 2 million teenagers have blood glucose levels higher than normal, a condition called pre-diabetes. These children are also exposed to cardiovascular disease in their 20s and 30s. According to a study presented last week at the American Heart Association’s Scientific Sessions 2008 in New Orleans, many obese children and teenagers have arteries as thick and stiff as those of 45-year-olds, a sign that such children could have severe cardiovascular disease at a much younger age than their parents unless something is done about it.

The new study conducted by the National Bureau of economic Research (NBER) questioned whether it would be practical to impose a ban on fast-food TV ads – something only Sweden, Norway and Finland have done.

“We have known for some time that childhood obesity has gripped our culture, but little empirical research has been done that identifies television advertising as a possible cause. Hopefully, this line of research can lead to a serious discussion about the type of policies that can curb America’s obesity epidemic,” said economist Shin-Yi Chou of Lehigh University in Pennsylvania. Chou was helped in his work by Inas Rashad of Georgia State University and Michael Grossman of City University of New York Graduate Center.

The researchers measured the number of hours of fast food television advertising messages viewed by children on weekly basis. They found that a ban on fast food television advertisements during children’s programming would reduce the number of overweight children ages 3-11 by 18 percent while also lowering the number of overweight adolescents ages 12-18 by 14 percent. The effect is more pronounced for males than females.

Besides fast food advertising, television is also known to raise obesity rates both because children exercise less and because it can interfere with sleep. Many studies have shown that sleep-deprived kids tend to have problems with their weight and consequently high blood pressure, diabetes or other obesity-related diseases. Watching TV is also related to a high consumption of snacks, which raises kids’ odds to become obese. Parents should be aware that television is not a way of educating their kids. They should encourage their kids to go out as much as possible. They should learn to do outside activities together with their kids, because exercising can be beneficial for both their kids and for them.