I'm not a researcher. I don't claim to understand the inner workings of a research project. Nor do I understand how different studies looking at the same problem can produce vastly different results. And I really don't understand the result of this study, reported in an article titled "Physical inactivity doesn't cause childhood obesity."
Here is an excerpt from the article:
Metcalf et al. published their longitudinal study in the June 23, 2010 issue of Archives of Disease in Childhood saying fatness leads to physical inactivity, but inactivity does not necessarily lead to fatness.
In the study, the researchers followed 202 children of whom 25
percent were overweight or obese for 7 to 10 years.
During the follow-up, the children were asked to wear Actigraph
accelerometers for seven days a year to measure their physical activity.
The body weight of each child was measured
annually using dual energy x ray absorptiometry.
The researchers found the body fat percentage was predictive of
changes in physical activity over the following 3 years, but physical
activity levels were not predictive of subsequent changes in body fat
percentage over the same follow-up period.
They concluded "Physical inactivity appears to be the result of fatness rather than its cause. This reverse causality may explain why attempts to tackle childhood obesity by promoting physical activity have been largely unsuccessful."
The bold emphasis is mine. And I ask again: How can this be? If overweight results from an imbalance between energy in (calorie intake) and energy out (calories burned), how can one part of the equation have no significance? And why is it that when I (the physical activity specialist) finally tore myself away from the computer and began walking every day, I lost 35 pounds? I did nothing different on the energy-in side of the equation; I simply began making sure I burned some of the calories I'd consumed...