We don't need a new way to torture our figures with figures, writes Victoria Lambert
If you woke up this morning feeling a bit fatter than usual, please don't blame yourself. Instead, let's all shake our chubby fingers at Oxford mathematician Nick Trefethen, who has come up with a new way to measure normal human body weight. The professor has decided that those of us who are shorter than 5ft 7in are more overweight than we were yesterday.
His theory is that the body mass index (BMI), used by doctors to calculate whether patients are underweight, normal, overweight or obese, is flawed.
Prof Trefethen – who hasn't declared his own weight or height, incidentally – thinks that this traditional formula doesn't allow for the extra padding that taller people naturally carry.
In his version, your weight in kilograms is multiplied by 1.3, with the answer then divided by a person's height to the power of 2.5 (rather than your weight in kilograms being multiplied by your height in metres squared, as previously).
Still with me? In short, if you are Saffron Burrows (6ft), you can merrily finish that box of chocolate liqueurs left over from Christmas. But, sorry, Lady Gaga (5ft 1in), it's celery for you from now on.
To clarify, if you are 5ft 4in – the height of the average Irish woman – and you weigh 10st 3lb, last night you were considered normal. Today, in the light of Trefethen's workings, you are overweight. And to be thought obese, you now only need to hit 12st 4lb, not the 12st 7lb of yesterday.
Thanks for your trouble, Prof, but we women really don't need a new way to torture our figures with figures. We don't need you to move the goalposts – even in the name of scientific research.
We don't want you to make us feel porkier. We can do that all by ourselves, usually by the first latté of the day.
Worse still, meddling like this will only encourage us. Our collective neurosis is such that we are now bound to do anything we can to get back to that place called "normal".
Take the current craze for the 5:2 diet. No, those are not the odds against failing to keep to January's good intentions.
The 5:2 diet is the slimming plan de nos jours, the "new" Atkins, Dukan, F-Plan etc, which involves eating what you want for five days a week, and keeping to fewer than 500 calories (which the diet's inventors describe as fasting) of fairly limited foods for the other two.
Adherents – the diet is spreading like a cult – are evangelical, claiming to drop 20lb here, 30lb there, with – the holy grail of dieting – no effort at all.
It's as though there are giant vats filling up with yellow adipose tissue, human lard banks, outside every supermarket, where you can dispose of a muffin top after two days' ferocious control, before popping in to stock up on, say, muffins for the next five days of gorging delight.
What are we, Romans? Decadently making bedfellows of purging and pleasure? How sick is that?
You see, Prof, working diligently at your spreadsheets among those slender dreaming spires, out here in Weight Watcher world, ordinary women have been driven to the point of insanity. For us, it feels normal to stuff and starve, to eat like Paleolithic Man one day and to use vibrating forks and wear leggings imbued with caffeine the next.
To spend all our salaries on African herbs, juicers, and laxative fat-binders that are so powerful the instructions include carrying a change of underwear.
Some of your scientific peers, at Tufts University, Massachusetts, in America, have just released research on how we feel about food. They found, in a study of 2,000 people, that we are so conflicted about food that one-in-three women eats snacks in secret, with one-in-10 hiding food under the bed.
Two-thirds keep their munching secret from their partners, with half saying they feel guilty after enjoying a treat.
So, Nick, there is nothing helpful about a new formula to tell us if we're obese or merely overweight. We know our shape. We know if we're fat or thin, because, unless we're Kate Moss, we're fat. Why? Because we're women, and that is simply how we – that is, most of us – see ourselves.
Maybe the BMI isn't perfect.
But do you think we didn't know that? Of course we did. There are, after all, only two true tests of size. The first: how tight are my favourite jeans? The second: can I still get into my wedding dress? Go figure that out.