Obesity rates are increasing pretty much everywhere, but nowhere is the obesity problem as massive as in the United States. And nowhere else is television viewing such a cultural focus. With ever increasing viewing times, now about 4 hours a day, one has to wonder what drives Americans to spend so much time in front of the TV with a beer and greasy finger food. Maybe it is the lack of alternatives. Indeed, walk around almost any US city and you will find very few people outside, in a large part because there is nothing to do outside: few parks, no pedestrian areas, no river fronts, etc.
Maoyong Fan and Yanhong Jin show that this does indeed matter for obesity, in particular childhood obesity, which is the most difficult to reverse. One needs to differentiate by various characteristics, though. Parks work particularly well for girls in unsafe neighborhoods, but not as well for white adolescents with high incomes. Now switch that TV off and go outside.