Our diet is in large part a result of government intervention. Farm subsidies make distort the price of corn based products (HFCS for instance). The existence of government run schools prevent choice in school lunches.

However I do agree that government should play a role in regulating second hand smoke, as that is an instance of one individual using coercive force over another (making me inhale your smoke in public). Although even that issue is a slippery slope. Do we ban cars because their exhaust is toxic?