I've been saying that forever - the math just isn't there.
Thankfully other people have been out there proving it.
People like Drs. Westerterp and Speakman who in May of this year published a fascinating paper in the International Journal of Obesity.
The paper looked at energy expenditure experiments conducted since the 80s. The experiments were gold-standard style as they used doubly labeled water to track results. Many health professionals, the media and the general public might assume that since obesity rates have risen dramatically since the 80s, energy expenditure (the scientific term for activity) must have declined in turn.
Imagine their surprise to read this paper which showed that not only has the developed world's average daily energy expenditure remained the same, it does not differ significantly from that of the third world (a conclusion also reached in that paper I blogged about that compared the energy expenditure of suburban Chicagoans to Nigerian subsistence farmers).
Given that there are ultimately only two components to energy balance (in and out), and given that "out" over the course of the past 30 years has remained the same, once again I'm going to say if we want to see any progress in the war on obesity it's going to have to come from shifting the focus to "in".