Christina Patterson: Sister, stop stuffing your face

At regular intervals in my adult life, I've been through the following ritual: I'm sitting reading a book when a gargantuan creature comes lumbering over, and marches me to what might or might not be a scaffold. After a few adjustments, I am placed against a wall. Moments later, after staring at a chart, and making a calculation that is clearly more taxing than the post fiscal stimulus national debt, the creature nods. Yes, she says curtly, my BMI is OK.

The creature is, of course, a nurse and yes, my BMI is OK. Hers, however, is not. But we are not here to measure her BMI. We are here to sit in a waiting room for hours, ideally one that's full of giant tellies with the volume turned up to maximum level, so that I can then be summoned to see a registrar who may or may not have read my notes and discuss the myriad ways in which my normal-sized body has let me down.

Other normal-sized friends have been told by giant doctors that they are fat. Doctors who don't chuckle heartily and present their verdict in an isn't-this-ridiculous-but-I'm-just-following-orders sort of way. Doctors, indeed, who appear to have no sense of irony, no sense of humour, no sense of the surreal. Because it is surreal, I'm afraid, to be lectured on your weight by someone whose mass of accumulated adipose tissue is considerably greater than yours.

No one expects nurses to look like supermodels, or lap dancers, or air hostesses, or even like anything that might ever have inspired an erotic fantasy (the PVC "nurses' uniforms" at Ann Summers don't, I think, bear much resemblance to the current shapeless tunic and trousers), but you don't expect them all to look like Hattie Jacques either. And at least Hattie Jacques knew how to smile. You might, however, reasonably expect the custodians of the nation's health not to look as though they were about to consume the GDP of Iceland in medication for diabetes, and you might expect the custodians of the nation's health to at least have glanced at some of the leaflets on obesity they so lugubriously hand out.

More than half the NHS's 1.2 million staff are overweight, apparently, and 300,000 are obese. And now, in a marvellous example of "joined-up thinking", the Government has decided that it might be a good idea to increase "the credibility of health messages" by looking at the "behaviour of health professionals". By inviting NHS staff for – wait for it – a check on their BMI.

Well, let's hope it works. It might, I fear, take rather more than that for people who have survived three years of training in the human body and emerged convinced that it's an organism that functions best on chocolate and chips to spearhead the revolution we all need. Particularly when they're all miserable about their pay and convinced – in spite of the counter-evidence of great swathes of the day spent chatting – that they're collapsing with stress.

But we've got to start somewhere, and at least they have a job – a job, unlike many of their patients, they're unlikely to lose – and maybe it's time they started to do their bit in helping to transform this lumbering, wheezing, tax-guzzling dinosaur of a national health service into something "fit for purpose" (in John Reid's ghastly phrase) – or even something that's just halfway fit.