There are lies, damned lies and vital statistics. And as Fern Britton has discovered to her cost this week, while the first two may be borderline forgivable the third has the potential to trigger national outrage on a scale not seen since the Argies invaded the Falklands.
The story so far ...
Fern, once hailed as that most laudable of creature in contemporary society — the "real woman" — has in recent years slimmed down from what she once described as a "cuddly size 16." But may, in fact, have been an elasticised waistband or two bigger.
Fern was undoubtedly a big girl in her day. But she was also a good-looking woman. Indeed many, many female viewers of This Morning, the TV show she presents, loved her precisely because she was — like so many " real women" out here in the real world — a bit on the chunky side. In a celebrity world where youth and emaciation are valued, Fern had become the poster girl for what used to be called middle-age spread.
The rot may have set in when she was invited to apply her middle-age spread to Ryvita. The clever tongue-in-cheek advertising campaign which she fronted for the crispbread company featured shots of her body digitally enhanced to look very slim.
It must have struck Fern (as it would any of us) that this was how, with a few stones off, she could look. It must also have occurred to her that there would be a certain poetic irony in using the pay cheque for the ad campaign to finance just such a transformation.
She paid several thousand pounds to have a gastric band inserted. It is an operation which in these days of obesity epidemic seems to be as common, if not as cheap, as getting your belly button pierced.
Where did she go wrong? She didn't tell the rest of us about it.
When her commendably loyal husband was asked by an interviewer how she'd managed the weight loss, he tactfully and not entirely dishonestly said it was down to eating less. Fern did not leap in to expand about the band. It is for this that she has this week been monstered by the media. Front page after front page has decried her "deception". Acres of copy has been devoted to her "crime." Television and radio debates have agonised over the issue. She's had even more bad publicity than Robert Mugabe.
For overweight readers and listeners much of this abuse and sneering about her one-time sizeable shape will have felt very personal indeed.
The message being driven home is that the 'real woman' tag is really only a patronising sop. In media terms they see you as fat and contemptible. And if you try to lose the weight outside of the traditional diet path they will brand you a 'cheat'.
Why didn't Fern come clean about her gastric band in the first place?
Possibly because like most of the rest of us, she doesn't have the Jeremy Kyle gene that drives you to spill all your private business — emotional and intestinal — all over the gossip sheets.
Maybe she also feared ridicule or criticism for attempting to use a short cut to reshape her 'real woman' figure.
Some of course will argue that her real crime was that by not coming clean when her husband gave that interview she had, in effect, lied. But let's keep this in perspective. If she lied, it was a lie about a gastric band. Not about weapons of mass destruction.
Her biggest problem was that she fell foul of the body fascists. For all the talk about 'real women', the fact is that there is a size standard today — nothing over a 12, nothing under a Posh — to which women must conform.
We are obsessed with weight and food and body shape to an extent that we are unable to tell the difference between a real woman — and a real villain.
There are bigger monsters in our society than poor Fern Britton.
Oscar Wilde once castigated those Victorians who knew the price of everything and the value of nothing.
A century on we know the value of nothing ... but the calorie count of everything.