Not only does my five-cakes-a-day husband have cavity-free teeth, it now turns out he has the pulse rate of an Olympic athlete and the cholesterol levels of a gerbil.

Last week he took advantage of a medical health check-up, paid for by his employers, and came home bragging about the results.

"The doctor said I have one of the healthiest hearts he has ever come across," he said, pouring himself a large lager and opening a family-sized packet of Mignons Morceaux.

"And, apparently, I have very little bad cholesterol and lots of good cholesterol. And my pulse rate is 57, when the average is 72."

"Excellent," I replied, wearily tucking into a plate of boiled broccoli and carrots as part of a very dull diet I had decided to try for the week.

"Couldn't the doctors find anything wrong with you at all?"

"I'm a little overweight," he said, pinching a bit more than an inch on his waist. "Maybe I'll cut out the 11am bun."

My husband is clearly one of the fortunate few for whom bad eating habits haven't had a lasting effect.

When I first knew him it wasn't unusual to see him wolf down a half-pound bar of chocolate and drink a pint of full-cream milk as a between-snacks snack.

His capacity for eating is legendary among his oldest friends, many of whom have regaled me with many tales of my husband's piranha-like tendencies in restaurants, at dinner parties, on picnics and in the privacy of their own larders.

I've noticed the quantities have become smaller during the years that I have known him.

But there have still been occasions when his hunger has turned mealtimes into a feeding frenzy.

The first time he met my parents I recall their astonishment when they saw the speed at which he piled food on to his plate and devoured it.

He was ready for seconds before they'd had a chance to pick up their cutlery.

In those days he did very little exercise. Now he does regular work-outs at a gym, which must counteract some of the side effects of the chocolate muffins.

But that can't be the whole answer. There must be a genetic element, too. He's obviously got a special cake gene that turns all that bad cholesterol into the good stuff and keeps his metabolism working at peak rate.

Naturally, I'm rather jealous. I only have to think of a muffin and my bum doubles in size.

And I'm sure I'm overweight (hence the diet) but I daren't step on to the scales for fear that I'll become too depressed and start imagining the entire contents of that lovely patisserie in Trafalgar Street.

In fact, I've become so obsessed with my husband's health that the other night I dreamed he was selected to become an astronaut on account of his "good cholesterol".

"WHAT THE HELL IS GOOD CHOLESTEROL?" I'd shouted at the Nasa crew captain as we wandered through my dreamscape. "AND WHY DOES MY HUSBAND HAVE IT?"

"We think he may be from another planet," said the captain in a hushed voice.

"Ah, yes," I'd whispered. "That explains everything."