Make it a condition of being treated by the NHS that you waive the right to sue except under certain circumstances like Shipman. Just in compensation that saves £2.5 billion a year I believe.
I'm no doctor but I am pretty sure it wasn't 35 stone of water retention. I think the general point in any case is that people need to take some personal responsibility for their lives (and not just health). The difficult part is operating this principle in practice fairly.