So we shouldn’t ask lawmakers to prove that a) obesity is an imminent threat and b) banning large sodas will defeat that threat? Because that’s certainly the premise.
Well, yes, but that is the progressive standard on everthing – identify a “threat,” and then propose whatever you’d like in the name of doing something about the “problem,” whether your proposal will actually mitigate the problem or not.
Finally, ignore the question of whether your proposal violates constitutionally-guaranteed liberties in America.
Rather like banning some “ugly guns.” Or some unfashionable drugs in certain circumstances (but not in others – see the compulsory speed-freaking of American boys).
The ultimate name of this game is control, not problem solving. Don’t forget it.