In a historic reversal, in today's America the rich are thin and the poor are fat. But we now hear that it's not peculiarily American, but just the arc of prosperity; other affluent societies are heading in the same direction. Lionel Tiger in today's WSJ sums it up very aptly and with a dash of fun ("Please Sir, Can I Have a Bit Less?").
And eating habits had to become part of political platforms because everyone else's health is now the source of an externality. Think of it this way: today's LA Times includes "China tries in vain to keep bellies buttoned up ... Beijing has been on a manners kick for the last few years, but on the hottest summer days, there is no stopping men of all ages and shapes from rolling up their shirts and exposing their tummies."
Managing all of these externalities was never going to be easy.