A ban on fast-food ads in the United States could reduce the number of overweight children by as much as 18 percent, U.S. researchers said.

Shin-Yi Chou of Lehigh University, Inas Rashad of Georgia State University and Michael Grossman of City University of New York Graduate Center measured the number of hours of fast-food television advertising messages viewed by children on a weekly basis.

The study, published in the Journal of Law and Economics, 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.

"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," Chou said in a statement. "Hopefully, this line of research can lead to a serious discussion about the type of policies that can curb America's obesity epidemic."

However, the researchers added that although such a ban would be effective, they question whether such a high degree of government involvement -- and the costs of implementing such policies -- is a practical option.