Marc Ambinder, who has done a great deal of research on the subject, takes issue with what I have written about obesity. Since he wrote carefully, I think it deserves a careful response.
McArdle approaches obesity as if it were a Foucauldian construct: a category invented by the government to justify an exercise of power. The government has no business intervening on the level of individual choice and it shouldn't get into the business of behavioral suasion because it always fails. She's right to note that information about health risks associated with overconsuming fat and sugar and salt are saturated throughout society, even supersaturated. Everyone knows how bad this stuff can be. For her, that's the end of the argument. Government can help to provide information about how to make better choices, but it cannot and should not try to persuade people to make better choices. Indeed, the push for people to make better choices produces the stigma that makes the bad thing bad in the first place.
That's not quite right. Obesity exists. For very heavy people, it's a serious health threat. It is to some extent arbitray, and indeed is invented by the government, which is true of many classifications. GDP is also arbitrary and invented by the government, but it is no less useful a concept because of that.
I don't really care if the government tries to persuade people to make better choices. But in general, government efforts to persuade people have failed. Government efforts at transparency are useful--it was the surgeon general's report on smoking and cancer that started the downward trend in cigarette consumption (and, natch, some of the upward trend in our waistlines). Government coercion has also proven somewhat effective--cigarette taxation and anti-smoking laws have, as far as I can tell, helped cut into smoking quite a bit. But the middle ground, where they just try to persuade us to change our ways, has given us genius moments like this: