In a new paper out in The Journal of Law and Economics, Shin-Yi Chou (Lehigh), Inas Rashad (Georgia State), and Michael Grossman (CUNY) study the effects that fast-food advertising on TV has on overweight children. They estimate that banning advertisements would decrease the number of overweight children by 14 to 18 percent. A ban might not be optimal, however, since it may also reduce the amount of information available to consumers. (For example, being informed that it is Monopoly time at McDonalds could arguably make you better off.)
The authors go on to show that eliminating the "tax deductability of would produce smaller declines of between 5 and 7 percent in these outcomes but would impose lower costs on children and adults who consume fast food in moderation because positive information about restaurants that supply this type of food would not be completely banned from television."
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