Derrick Jackson’s call for “a war on soda and our sedentary ways” is only half correct (“All Quiet on the Fat Front,” October 11). Americans need more exercise; there’s no doubt about that. The U.S. Bureau of Economic Research recently determined that 60 percent of our national weight gain can be traced back to sedentary lifestyles.

But a war on soda? I don’t think so. The supposed link between soda and obesity is snowballing into the stuff of urban legends. The most frequently cited source for this claim is a 2001 Harvard study published in The Lancet. About this, the Centers for Disease Control and Prevention has written: “There are no data from the Harvard study that allow us to make an estimate of what proportion of obesity might be accounted for by changes in soft drink consumption.”

A link between soda pop and overweight kids may seem intuitive and obvious, especially when promoted by self-anointed “public interest” activists. Intuition, however, is no substitute for hard science.