I see what you mean. The thing is, fast food is still food, and you can get it fast (thus the name). It still has some positive benefits, peple burn fat at significantly different rates, etc. I could see the point in banning consumption of certain types of food depending on your body weight/heart rate, but I doubt I'd support it. That's a little more information than I want McDonalds or Burger King knowing.
I don't think it's hypocritical of the government to ban smoking but not fast food unless you look at it from a very simple perspective of the numbers of deaths per year. In which case the government might have to end up banning having children, driving cars, flying, maybe even certain types of jobs due to the number of deaths being more than those resulting from various crimes to prevent from being hypocritical. Heck, a lot of people die from various diseases...should the government ban having those diseases and impose severe penalties if you get/have one?