There is no full-length mirror in my house.

I used to stand on the loo, leap and catch myself on the way down for a brief second in the guest bathroom one. That seems far too energetic now so I make do with my own bathroom mirror from the waist up and the glass door for a full length, outline only, reflection if the light's right.

Fortunately or, as it turns out, unfortunately, the mirror in my bathroom gives a kindly light to my features because of its positioning. My lines miraculously disappear, my hair seems almost perfect in both cut and volume and never seems to need the roots streaked.

I am aware of its magic properties, so take them with a pinch of salt, but it propels one into the world with a confidence, even if it is a misplaced one.

How misplaced I discovered last week in the box-like, strobe-lit changing room of Max Mara's in Toulouse's smartest shopping street.

I was fairly shaken before I got there, having somehow gone momentarily insane on the autoroute, then wondered why cars were tailgating, flashing, beeping me or screeching around me, drivers' fingers raised.

"For God's sake, I'm in the slow lane," I screamed back at them waving a similar finger in response.

"Actually," said a weak voice from the passenger seat, "You're in the fast lane."

I wondered why C had gone uncharacteristically quiet, and now I knew.

"Merde."

It is impossible for me to drive and talk when navigating the ring-road motorway approach to Toulouse. I should have remembered that.

So I was probably still rattled when the horror revealed itself.

Sweet God in heaven. I closed my eyes and came at it with a sideways flicker. Yep, still there.

My moan brought a shout from C: "Everything OK in there?"

"Don't come in," I yelled back. "Whatever you do, don't come in. And don't let the assistant in."

A large skin-covered tire now snaked around my waist between bra and pants; my bosoms had inflated overnight; my upper arms were blobs of swirling blubber. And the chin and neck ... for once I'm finding some things just too painful to share.

I knew people put on weight when they stop smoking but I was blithely unconcerned, as I often have to force myself to eat anything more than a bag of crisps and an avocado. Or a plate of oven chips.

I was, anyway, under my normal low weight and was back into clothes that hadn't been out for a few years. Mind you, neither have I really.

And I was right. Food still doesn't particularly interest me; my taste buds have not awoken from a chemically induced coma, and all tastes exactly the same. Basically, boring after a few bites.

Strangely I had noticed the wine tippling was going upwards; apparently another known aspect of chucking the fags, as the mind/body searches for new happiness sensations.

But I am now walking around 80 minutes every day so it should cancel out, shouldn't it? Rhetorical.

(I have lumps in my legs that I understand may be muscles, even.)

Then, two months on, I awoke to tighter clothes and an overlap of flesh once the jeans button was fastened. I could feel padding on my backside and my hips, yet my legs were still skinny as a sparrow's.

I mentioned it to the doctor when I was getting my nicotine prescription. Apparently it's normal. Smoking, particularly when you have chronic obstructive pulmonary disease as I have - there, said it - makes the body work harder to get oxygen around it.

The metabolism is on high-speed dial and often, like me, weight is actually lost.

"But I'm still on the nicotine," I wailed. "Surely that counts."

"No," he said, "in fact most people put on between five and seven kilos. You're lucky; you're nowhere near that. You're fine."

I will come clean now and tell you that had I merely given up cigarettes to prove I could, or to save money, I would have walked straight out of his surgery and into the tabac.

"Hi honey, I'm home. Missed me?" I would have said to my supplier with a raffish wink; slapped my bank card on the counter and taken the cartouche of 200 fags I once bought every six days. Or was it five?

I would have ripped it, and the first packet, open, before I'd hit the door and I would have inhaled with the desperate, loving hunger of the reunited addict.

And the few pounds of fat would have melted in quick time with each lungful of pure disabling, glorious poison as it infiltrated those now half-dead lung filters.

But I didn't, because I've backed myself into the corner and the awful spectre of carrying my oxygen supply frightens me more than the flab appals me.

So, I will return to the faux reassurance of the bathroom mirror, look out the Spanx, reluctantly cut back on the vin, and just breathe.

My son will accept me a touch plumper in his wedding photographs.

He prefers that I might, please God, live just a little while longer.