In the long run obese people die sooner thus saving us money. Sure, they are more expensive to treat on an annual basis, but since they die sooner, their lifetime health care costs are less.
If Obesity Saves Taxpayers Money, Should It Be Encouraged?
I wouldn't say it's good to encourage it, but maybe you could be a bit more hands off as far as trying to legislate behavior goes.
We should also be able to call it out for what it is, and not be socially shy about ranking the cost of services based on someone's body type (i.e. backside dimensions determine the number of seats you need on the train, bus, or plane and hence the cost). Private business would like to do this in many cases but social pressures prevent it.
It's quite obvious that some people just don't fit in the seats on the train I take regularly. They either take up 2 seats because one leg goes cocked up on the seat next to them to prevent them from tipping off forwards, or they take up two facing seats because the person across from them wouldn't fit.
So, you should have to pay the cost of being obese in society and then decide whether it's a great thing to be fat or not, all things considered. I don't want to subsidize it by either paying more because they put fewer seats in the vehicle or by being browbeaten against asking someone to only take up the one seat that they paid for.