This was such a weak article:
NYT: Is junk food really cheaper?
The column starts off with an argument that fast food is actually more expensive than natural food. As proof, the author picks an anecdote completely out of thin air. In his hypothetical case, for a family of four, fast food is more expensive than healthy food. Take that, statisticians! He goes on to make the really insightful point that there are lots of things people could do to live cheaper - like drink water instead of soft drinks. He then goes on to talk a lot about how the problem here is really cultural: people are lazy, and don't like to cook. His solutions include changing said culture. The column ends with a complete 180, culminating in vague references to statist political solutions to curb consumption of processed food.
The only useful thing he does is bring up the analogy with the anti-smoking campaign. Consider for a second: what would you say if, instead of taxing cigarettes to $ 8.00 per pack where they are now, the government was subsidizing them to $ 1.50 per pack? And then imagine some jackass wrote a NYT column about how we just have a crisis of culture and that the OBVIOUS solution was for people to just get some willpower and quit smoking. Never mind stopping government hand-outs to tobacco companies (in this hypothetical case).
This is the reality of the nation that we live in: the government essentially pays people to eat fast food and drink soda. That is the 100% truth. We can talk about culture, paternalism, and lots of other things but it really comes down to incentives. Whether or not fast food is cheaper than natural food is really irrelevant - thanks to subsidies, fast food is cheaper than it would otherwise be. Period. People would consume less processed food it it was appropriately priced. Food industry subsidies are an example of big-government corporate socialism at its worst.
Once we all agree that we shouldn't be paying people to eat unhealthy food, we can wade into the area of whether or not we should tax unhealthy food. I think reasonable people can BEGIN to disagree on that point. That being said, taxes have to come from somewhere. Why not tax things that we shouldn't be doing (smoking, eating unhealthy food) instead of taxing things that we should be doing (working hard / income taxation)? Especially when people expect the government to pay for their health care at the end of life, its not unreasonable for that government to try to discourage the most unhealthy behaviors. Whatever; like I said, taxing fast food is an issue we can debate; that we subsidize fast food is not a point for debate - its a travesty.