Of the many lies told by politicians and policy experts with an axe to grind, the most pernicious is the most frequently proclaimed: “This will save money in the long run.” Since in the long run we are all dead, the sheer nonsense of most such claims is usually ignored.

The pattern is always the same. In the short term, ideas that supposedly save money in the long term cost a lot. Advocates call them “start-up costs”, as though such things can safely be ignored. In the medium term, spending rises still more. And in the long term, the idea that is going to save money ends up costing more than anyone imagined possible.

There are few clearer examples of such insanity than the current obsession with obesity. Yes, being fat is a bad thing, but the idea that, because obesity is bad, spending government money to try to tackle it is good is the perfect illustration of the this-will-save-money-in-the-long-run mantra. After all, since obesity makes us ill and costs the NHS and the economy, it stands to reason, doesn’t it, that we’ll save money overall if the Government tries to do something about it?

Fine. Now take a guess at how much of our money this Labour Government has spent on attempting to make us thinner: £100 million or so? £500 million? £750 million? £1 billion? Don’t be so stupid. It’s not possible.

Yes it is. The Department of Health claims that £9.6 billion has been spent on projects that reduce obesity across all government departments. You read that right. Nine point six billion pounds.

And guess what? Like all ideas that involve huge spending today to save money tomorrow, it has been spent to nil effect. All the figures show that we are becoming more, not less, obese. “We still need to raise awareness,” says Dame Yve Buckland, chairman of the Health Development Agency.

Of course she says that. That is because abject failure is taken as a sign, not that the idea should be scrapped, but that it needs more “investment” if it is to succeed.

And so, right on cue, we learn that the Prime Minister himself wants, in a stroke of genius, to link spending money on obesity with the Olympic bid. It is what is known as synergy. Take one giant waste of time and money, the Olympic bid, and combine it with another, tackling obesity. Since neither stands the slightest chance of success, putting them together into one mega-waste is sheer inspiration.

Mr Blair has decided that he wants “an ambitious delivery strategy, using the Olympic bid as a catalyst, to develop more innovative and interventionist policies across the public, private and voluntary sectors in both health and sport”. So there will now be a “£1 million publicity campaign showing how gardening, walking to work and even housework can help to make you fit”. Hmm. That is a bit limited, surely. Best to add the information that breathing in and out keeps you alive.

The real problem, according to a report yesterday by the analysts Dr Foster, is that “many obese people do not have access to expert advice to help them lose weight.” More than half the primary care organisations in the UK have no organised weight-management clinics. Heavens! How on earth can anyone lose weight without a weight-management clinic?

Well, here’s a radical idea. The solution is not spending large sums of public money. It is fat people going on diets and taking exercise because they realise they need to.

I know what I’m talking about here. In the past few months, I have lost 27lb, with more to come. And I have lost it because I looked in the mirror, not because a civil servant told me to diet.

The author is available for hire as a dietician for £9.6 billion.