Like all failing projects, or popular cults, the NHS needs scapegoats. Britain’s health service is plagued by an endless stream of deviants who are a ‘burden’ on its resources. Otherwise known as patients, they are the drinkers, smokers and fatsos who, we are told, will bring the NHS to its knees unless lifestyles are regulated by the state.

Smokers were a useful scapegoat for a while. Now it’s the obesity ‘time bomb’. As Simon Stevens, the chief executive of the NHS, recently put it, ‘The new smoking is obesity.’ He claims that fatties will cost the NHS far more than the £8 billion he wangled out of George Osborne before the election.

Much of the fear about obesity rests on the belief that it is a spiralling epidemic. Properly defined, an epidemic is a temporary outbreak of contagious disease in a specific community. The gradual rise of corpulence in Britain in recent decades is neither fleeting nor infectious nor localised. The term ‘epidemic’ has been adopted to stoke the illusion that being fat is an issue of public health requiring government action when it is really an issue of personal health and private behaviour.

Whatever we choose to call it, obesity is not spiralling. Rates of childhood obesity are in fact falling. Adult obesity is flatlining. So the hysteria can only be maintained through predictions of a future catastrophe. In 2006 a Department of Health report predicted that 28 per cent of women and 33 per cent of men would be obese by 2010. The fateful year came and went with obesity rates of 26 per cent for both sexes.

In 2007 the Government Office for Science issued a report predicting that ‘by 2015, 36 per cent of males and 28 per cent of females will be obese’. At the last count, the rates were 26 per cent and 24 per cent respectively, which is to say that they had fallen slightly since 2010.

A few weeks ago campaigners had the good sense to make a prediction for the more distant future when they claimed that three-quarters of Englishmen will be overweight or obese by 2030. Considering that there has been no rise in this category since 2001, this seems as unlikely.

If Britain does not feel as if it is in the grips of a fat epidemic, these wild predictions are designed to make us believe that it is only a matter of time. Since obesity is linked to a number of diseases, it is easy to believe that fat people take more than their fair share of NHS resources. But this is a fallacy. Without question, some people wind up in hospital for ailments that can be attributed to their girth, and there are costs attached to such admissions. But it is equally obvious that if someone does not die from one cause they will die from another. The real question is whether the diseases that afflict slim people are less expensive than those that afflict the obese. The evidence suggests that they are not. Moreover, slim people tend to stay alive long enough to endure cataracts, broken hips, dementia and all the other blessings of old age that place a strain on the NHS.

In a 2008 study of lifetime medical costs, Pieter van Baal and colleagues found that obese people cost the health service less than the ‘healthy living’. Smokers cost even less. In that sense, obesity is the new smoking. Like smoking, it saves the state billions of pounds in unpaid healthcare and pensions. This has been established in numerous economic studies over several decades, but nobody wants to admit it, least of all those who run the NHS.

It is longevity, not premature mortality, which places a burden on public finances. If the NHS ever collapses, it will be because we are living too long. When the NHS was created, life expectancy was 68. It is now 81. Despite all the ‘time bombs’ and ‘epidemics’, life expectancy is predicted to be 87 by the end of the next decade. The day may soon come when the average citizen spends more of their life in education and retirement than they do in work. This may well be unsustainable, but it is not the fault of drinkers, smokers or fatties. No one is doing more to save the NHS than them.