With cigarettes, it's pretty certain that the cigarettes are the primary cause of disease much of the time. I don't think it's that simple with carbohydrate--it's fairly easy to demonstrate that once somebody has certain diabetes or insulin resistance, carbohydrate restriction will be effective, but a fairly high carbohydrate diet doesn't seem to cause much in the way of diabetes or insulin resistance outside of our modern diet and lifestyle. Plus, make carbohydrate too expensive to eat--and everything else gets a little more expensive as well, there's more competition for the avocadoes and bacon. This is one reason I want more study into various types of intermittent fasting, like Dr. Fung says, everybody can afford it.

Targeting sugar and corn syrup is a little less problematic, whether it's enough to decrease obesity or not (I suspect it will help) it should contribute to health. But I don't really want to be taxed into compliance, when you get down to it.

I don't think the tax has to be all that high, though--all the noise around a tax might be enough to raise awareness of the problems with sugar.