In time, don't be surprised if your doctor will select who he will see depending on their condition: ie if it's self-inflicted, you will be waaay down on his priority list.
That's fine so long as fat people, drug takers, smokers, high risk sportsmen can all opt out of paying a large chunk of National Insurance to put towards private insurance.
What next, scanning everyone at birth to ensure hereditary defects are not covered. What about all the "Mental Health" suffers these days self harming. Ban fixing that on NHS too.
Not forgetting irresponsible adults that have multiple kids when their jobs can't even support themselves. Get them & family off NHS too? It was their choice (or lack of responsibility) to have kids.
What country are you from ?
My mate at work has spent his life doing downhill extreme biking and been in hospital just about every year having broke most things in his body multiple times. Me, who is slightly obese, has managed to get to his 50's with 1 visit to hospital when I was four and have no medical conditions. I do cycle 20 mile to/from work, walk at lunch break when not raining and my resting heart rate is under 50 with normal blood pressure.
Have three other people I know that are perfect body weight but in and out of hospital/counselling due to drink problems, two were even told they would be dead in 12 months unless they stopped (fortunately they did stop).
Its easy to pick out fat people with it being visually obvious unlike many other, often self-inflicted issues people have.
By all means tax food based of its excessive fat/sugar/salt content similar to pricing people off fags (and in Scotland booze to some extent).
I notice in KFC since the sugar tax on drinks they have posters up saying over 75% now switched to Max Pepsi. That's the way to do it (I've not touched sugar in drinks for at least 20 years).