Yes, it’s what you do or don’t do with your time, money, and mouth. yes, there are many options available and many influences that often direct your time, 
money, and mouth away from healthier choices. But…can society, politics, and the private sector work together to reverse the trend toward obesity in america effectively? Can it, or should it? Two separate questions. Of course, if you believe as I do, that we’re all in this together – we healthy people pay for the choices of others even by our own private health insurance, and even life insurance, policy premiums because of demographic statistics that are actuarialized to determine rates. Furthermore, any public health costs are escalated to bank-busting levels by choices made, and fostered, by the many systems in our society.
This article in the Times addresses the possibility that the public and private sectors could re-tool themselves to improve our diet and our physical activity habits. It’s by no means comprehensive in this endeavor but it’s a start in getting folks thinking that maybe there are things that can, someday, be done to reverse the slide into obesification: http://www.nytimes.com/2010/08/22/business/22stream.html?ref=health