One important detail has been overlooked in articles about obesity: Physical inactivity costs Californians far more than excess weight.

A study released Tuesday found that obesity in the state costs about $8.5 billion annually. Physical inactivity, meanwhile, costs more than $13 billion.

What are we doing to solve the problem of sloth? Unfortunately, not much. Gov. Arnold Schwarzenegger has campaigned to change the contents of school vending machines. At the same time, gym is going the way of home economics.

Kids’ caloric intake hasn’t changed in 20 years, but their physical activity rates have dropped dramatically. Admittedly, removing vending machines from schools is far easier than getting kids to exercise. Such an effort would require enormous commitment and political will. Fortunately, the perfect candidate for such a task occupies the governor’s office. He should use his prodigious talents to promote exercise.