"Once the government starts providing health care, it becomes a state interest how well you take care of yourself. Your behavior becomes a factor in government expenditure. If you smoke, drink, eat fatty foods, don't exercise, you are costing the government money, and therefore, subject to government sanction."
I've long held the belief that those wonderful little 'super saver' cards and key fobs we all use at our local grocery store provide a great infrastructure for the gov't to track and enforce our eating habits if gov't health care ever comes to pass.
Government has already gained acess to these records in some court cases where a party "needed" a list of purchased items as evidence.