Instead of addressing the hundreds of individual factors that influence our weight, the and trial lawyers have honed in on food — arguably the most lucrative target. At the same time, they’ve ignored a crucial factor that is the subject of an article in Sunday’s New York Times. According to Times reporter Gina Kolata, “the rise in obesity is a classic case of unintended consequences.” In this case, Kolata explains, much of the problem results from the decline of the “truly lethal habit” of cigarette smoking.

Kolata talked with CDC researcher Dr. David Williamson, who argues that smoking cessation has made us a fatter nation, but also a healthier one. Paraphrasing Williamson, Kolata writes that “a nation with an expanding waistline is in far better shape than one with a cigarette in its mouth.” After all, we’ve seen life expectancy go “up by more than six years over the past three decades, and heart disease, long the major killer, is on the wane.”

Dr. Neil Grunberg of the Uniformed Services University told the Times that smokers who quit “gain about 10 to 12 pounds on average,” in part because their metabolisms have slowed down. Several studies have quantified the effects of this phenomenon. A National Bureau of Economic Research study found that for every 10 percent hike in cigarette taxes, the number of obese Americans increased by 2 percent. Considering that we’ve seen a 164 percent increase in cigarette taxes since 1980, the authors believe that as much as 20 percent of the recent increase in obesity is due to Americans’ declining tobacco habits. Co-author Michael Grossman notes in a recent essay:

Cigarette smoking is still the largest cause of premature death among Americans; pushing smokers to quit will have obvious health benefits. But our results and those of other economists also suggest that these efforts contribute to the rising prevalence of obesity.

CDC researcher Katharine Flegal corroborates Grossman’s point in an article recently published in The New England Journal of Medicine:

Among smokers who had quit within the past 10 years, there was a large increase in the prevalence of overweight … Among men, approximately a quarter of the increase in overweight (2.3 of 9.6 percentage points) and among women, approximately a sixth (1.3 of 8.0 percentage points) could be attributed to the cessation of smoking.

Flegal told the Times that the effect of smoking cessation on obesity “may be even bigger” than her study indicates, because of the people who “never smoked in the first place.” Add to that a canon of research indicating that physical inactivity is a far greater factor, as opposed to eating habits.

“I sure would like for people not to be obese,” Dr. Williamson told the Times. But he added that if people got that way because they didn’t smoke, then “maybe the sky isn’t falling quite as much as we think it is.”