Should The Fat be Given Benefits for losing weight?

In this post (benefits for the fat?), I looked at the economics of a guy who lost 30stone, including a £10,000 operation paid for by the NHS. Should we pay for people to have an operation like this? Is there a case for giving fiscal rewards for people who lose weight?

You may ask whether this idea could be extended

Does this mean we should give rewards for people to stop smoking? 

The government does very well out of smokers. It receives £7billion a year in tax revenue and smokers save the government pension spending because they die early. From a fiscal perspective there is no incentive for the government to encourage people to quite

Should we give people benefits who stop stealing?

The problem here is one of moral hazard. If you give people benefits to stop stealing, you provide an extra fiscal incentive to start stealing in the first place. This idea would not be beneficial, in addition to being morally reprehensible.