That's interesting. A large side of fries at Macdonald's would be $50 (though I suppose everything else would also jump a lot in price). Definitely creates a strong incentive to consume less.

Implementation wise, it probably would be best to begin at something like half a cent per calorie and then ratchet it up until we hit some target number (or until we discover it doesn't actually influence behavior). Then at the end of the year people get a $4000 dollar tax credit.