I was a three-litre-a-day-plus man, mainlining aspartame from morning 'til night in an orgy of caffeine and E numbers. So this was going to be tough, especially as I was weaned on Irn-Bru; carbonated drinks are in my DNA, and my first born will have Diet Coke in his veins and recycled aluminium for skin. I am a dietcokeaholic and this is my story.

The first morning of a brave new world, and it hurts. I cycle to the station, my head throbbing, my throat desiccated. I order water from Mike in the burger van. He looks perplexed.

"I'm giving up all fizzy drinks for a month," I say, and he shakes his head in bemusement. My first hurdle cleared.

At work I am grumpy, or let's make that grumpier. I have my sausage sandwich with an orange juice, but it isn't the same. No bubbles, no fizz, no tingle at the back of the throat. The day drags on, my cravings increase as my mood declines, and my colleagues wait for the temper tantrum or the collapse of will. It doesn't help that my next-door colleague, smug that she kicked the Diet Coke habit, sips Sprite Zero all day with innocent relish.

One week in and the headaches subside; another week gone and the cravings ebb, and I'm sleeping like a baby. I drink water and orange juice by the litre, and soon I am as spotty as a 14-year-old. After that, I reduce my orange intake, and my skin recovers.

And then came the big test: Paris, a Rugby International and several thousand hairy Scotsmen in skirts. My resolve failed at a Metro station. I had a hangover from Hades; the Coke machine was alight with the promise of fizzy, ephemeral, comfort. I had one long glug but something was wrong. It tasted false, impure, and I binned the rest.

So, only one indiscretion, and now, weeks later, how do I feel? Make mine a water.