Wandering round my local supermarket, I spied the following items among many others: low-fat fruit cocktail trifle, skimmed and semi-skimmed milk, low-fat wholemeal bread, extra-light mayonnaise, virtually fat-free yoghurt, Diet Coke, Slimline Tonic and, for the really desperate, reduced-fat guacamole dip.

Tesco and Sainsbury’s do not display these items out of highminded motives. They have been stocking them ever since the first trials showed the huge pent-up demand for any food or drink that could be ingested without unduly menacing the waistline.

Across the road in the book shop, the table in the middle of the floor was squeaking under the weight of Dr Atkins’s Quick and Easy New Diet Cookbook and half a dozen works by the same author, along with Fat Girl Slim by Ruth Watson, Joanna Hall’s Drop a Size in Two Weeks Flat and Dr Ali’s Nutrition Bible.

Every high street has its gym. Every upwardly mobile couple aspires to a personal trainer. Is there a hamlet so benighted that it cannot boast its own WeightWatchers’ club?

Never have so many devoted so much time, energy and money to seeing less of themselves. This is one national campaign in which individual initiative has blossomed unstoppably, without being much encouraged or much noticed by the authorities. For the political world — as always — wakes up to a new movement years after the rest of us.

So only now do we have plumped on our lap this great dropsical paunch of a report from the Commons health committee, warning us that we are engulfed in an epidemic of obesity and that if we do not eat less we shall all be choking on our own fat and half of us will be blind, or legless, or both.

In a strong field it is hard to think of a report from a select committee that has been more hysterical in tone, more cavalier in its use of evidence or less scrupulous in its extrapolations.

The MPs claim, for example, that the government will be forced to intervene “if the very existence of the National Health Service in its present form is threatened by costs spiralling totally out of control”.

Yet the National Audit Office, in its report Tackling Obesity in England, reckoned that this country had actually been spending less of its total health budget on coping with obesity than almost any other industrial nation — a mere 1.5%.

So it looks like being some time before the NHS grinds to a halt in a morass of adipose tissue. The methodology is so unreliable that I began to doubt the underlying statistics. Walking down a scruffy north London street, of the first 50 people I saw only four could be truly classified as obese and one of those turned out on closer inspection to be pregnant.

Even if we believe half the committee’s apocalyptic threats, its recommendations look puny and pitiful by comparison. Supermarkets, it says, should no longer put confectionery and snacks near checkouts, and food labels should carry more information about healthy eating. As though most children were incapable of ferreting out crisps and sweets wherever they are placed or would be deterred by something saying “Lollies Kill” on the label (although there is a minority of Fotherington-Thomases who take pleasure in rejecting items bought by their mothers if they contain too many E additives).

Would a National Walking Strategy really tauten the nation’s tummy muscles? Would the appointment of a Fat Czar revolutionise the government’s performance? The awful thing about these reports is that you can predict the tired old bureaucratic devices that ministers are bound to come up with.

Every now and then the committee gives the game away. In Finland, the only example it quotes of a country that has begun to reverse the obesity trend, the pressure came from consumers at the grassroots, not from the government. In other words, when and if the fattening eases off it will be our own decisions, not the government’s, that are responsible.