Well, in essence, it is not the government that pays the bills, it's the tax-payer. For me, under our health care system, I know that some of my money is being used to treat those that got themselves into a state of ill health through their own choices.
But I also know that they have been paying their share towards the NHS as well as paying tax, more than likely, on the very things that have caused their condition.
So, at the end of the day, as long as it is not bankrupting the system, I am inclined to say it is none of my business how they got to be 'ill' and I do not begrudge them the cost of their care. After all, I used to smoke a lot and I still drink a fair bit (more than the recommended limits at any rate). It would be hypocritical to expect to be treated by the NHS, should I fall ill, if I took the position that people who 'harm' themselves by their choices should pay for their mistakes out of their own pocket.
If the government represents the collective will of the people, then why couldn't the government tell you what to eat and drink and how to exercise? In a democratic society, if the majority decide what collective good will be served by their tax money, why couldn't they just decide that what you consume and how you exercise is simply part of the collective good?
In real terms, the food we eat and lack of exercise is bankrupting the system. One of the major reasons health care costs are going up is because people are getting sicker and sicker. So, from the collective taxpayer's point of view, perhaps we need the health nazis to save us from ourselves and promote the collective good?