No alcohol. No pasta. No coffee. And a breakfast of sesame seeds on berries. Jess Cartner-Morley endures the rigours of an intensive detox programme

It all started with a glass of water. Clear, blameless, fun-free, and ordered in a Soho bar by a friend who, in my mind's eye, is invariably attached to a strawberry daiquiri and a Marlboro Light. "Why aren't you drinking?" I ask, suspiciously. She's detoxing, she explains. I feel oddly let down and suddenly self-conscious about the vodka and tonic I'm looking forward to. I order it anyway, but my competitive spirit has been roused - and the next day I find myself deciding to investigate detoxing for myself.

Like many people, I drink alcohol more habitually than is sensible. And although I eat pretty healthily, my body is hardly a temple. OK, confession time: the allure of a detox programme has more to do with how much weight I hope to lose than the state of my kidneys. Shameful, but true: the 300 calories per glass I'll be "saving" makes it easier to turn my back on wine, at least temporarily. And, as if that weren't shallow enough, I can't help noticing that anyone who is anyone has declared themselves "intolerant" to wheat and dairy, and I wouldn't want to be left out.

Week one

I throw myself into the project with a convert's zeal, visiting Amanda Griggs, a nutritionist at the Balance clinic in Chelsea, south-west London. In order to prescribe a tailor-made detox programme, she conducts "sensitivity screening", sending a current via an electronic "pen" to acupressure points in my fingers, to ascertain my reaction to different food groups - a more sophisticated version of the traditional needle allergy tests. I am sceptical, but those foods that I long ago figured out didn't agree with me - dairy, oranges, peanuts - show up straight away, which seems persuasive. And while I have no allergies, it turns out that I am sensitive to foods I would never have thought of - mushrooms, tea, Marmite - which I will also need to cut out.

I buy a Muji brush for dry body brushing and a stack of detox books, and spend the evening swotting up with a final glass of white wine and a plate of wheat-laden pasta. I cheer myself up with the thought that I can eat chips if things get too miserable. As well as cutting out all the foods I'm intolerant to, for a six-week detox programme I am advised to eliminate wheat, alcohol, sugar, caffeine and red meat, and limit chicken and fish to two portions each a week. Amanda suggests thingssuch as sesame seeds on berries for breakfast, when my regular breakfast is toast and Marmite, bought on the way to work. I'll check, but I don't think the caff does seeds and berries. This is going to require organisation. What's more, I have to drink two bottles of water each day and Amanda has prescribed me a barrel of supplements, including liver and intestinal cleansers.

The first morning. I try to convince myself that hot water with lemon is a delicious substitute for coffee, and an apple just as appealing as hot toast, but it doesn't work. Already feeling sorry for myself, on the way to work I stop at Starbucks and order a decaf, soya-milk latte. It smells so disgusting I can't bring myself to drink it - clearly I am going to have to do cold turkey on my beloved coffee. Lunchtime at a restaurant is more successful: grilled fish and vegetables. At home, I eat rice with broccoli and leeks, which is fine.

By Thursday, I am enjoying the hot water and lemon - is it because my usually overstressed taste buds are working better, or because it makes me feel like Elle Macpherson? Breakfast is still a low point, but the other food restrictions don't bother me. Not drinking is odd, although I have found that a virgin sea breeze tastes almost the same as the vodka version. But a headache has set in by day two, and I feel tired and groggy. This is normal, apparently, while the toxins work their way out.

Amanda has prescribed a course of lymphatic drainage massage with the Balance therapist Carmel Phelan, to flush out toxins and reduce fluid retention. Carmel says I have congestion around my sinuses and in my arms. More body brushing is recommended.

The next day I wake with a runny nose and no headache. Carmel seems to have worked magic, dissolving the congestion in my sinuses. Tonight is Friday, and the first major challenge to my resolve: my best friend's birthday party. The problem is not so much wanting a drink as feeling increasingly alienated from the evening without one. Everyone else becomes merrier as I feel more tired. My stomach is bloated and painful. By 1am, I give up trying to get into the party spirit and head home for a peppermint tea.

The next morning, my digestive system seems to have finally adjusted to the new regime, and the bloating is gone. I feel energetic - for the first time all week, I can face the gym. And after a triumphant detox restaurant meal - oysters, sea bass, apple juice - I head to Fabric, where I dance till 4am on mineral water. I wake up the next day with sore feet from my dancing shoes, but a clear head. I eat poached egg with rice cakes and realise I'm in danger of becoming hideously smug.

Week two

The novelty is wearing off. I'm sick of people assuming I'm pregnant and/ or boring. One day I order a baked potato and salad for lunch and it arrives with butter, when I'd requested it without, but, frankly, I can't be bothered to send it back and have to wait all over again. I eat it, and feel guilty for the rest of the afternoon. At a fashion show that evening, I have one prawn canape with no dip, and one radish dipped in hummus. Starving and grumpy, tormented by trays of champagne and goodies, I go home early to eat asparagus tips dipped in a boiled egg - detox comfort food.

After another lymphatic drainage massage, my face and arms are visibly svelter - Carmel was right about the fluid retention - but I'm still not losing any weight. I don't understand it. Surely, the alcohol I've cut out alone should be having an effect. By Sunday, goody-goody food is starting to get on my nerves, so to cheer myself up I cook roast chicken with lots of roast vegetables in olive oil, char-grilled sweet potato and rocket salad, and grilled figs with sheep's milk yoghurt and honey - sort of allowed, but not what Amanda has in mind, I suspect.

Week three

Normally, although I would like to lose some weight, I don't actually care enough to remember not to clean out the bread basket in restaurants. In my new toxin-conscious state, I am constantly thinking about what I have and haven't eaten. One day, I find a rogue piece of pasta in my box of lunchtime salad. I immediately munch it, justifying this massive transgression by saying to myself that, since I didn't order it, it's "free". Am I losing my mind?

I fly to Lisbon for the weekend. Travelling requires planning: getting up early to have rice cakes before leaving the house, to avoid being tempted by Pret a Manger snacks. When Portuguese supper time finally rolls around at midnight, I ask for peppermint tea but end up with camomile, which nearly puts me to sleep - not ideal, because we're going clubbing now. I order a margarita and feel fantastic. And there's no need for more than one, as my alcohol tolerance seems to have regressed 15 years.

Week four

Halfway through, and time to report back to the lovely Amanda, who is entirely unfazed by my margarita blip: "Heavens! Don't worry about it. No point making yourself miserable!" I think I love her. She thinks I'm not losing weight because I'm eating too much fruit - and I probably have been overdoing the apples. I buy oat cakes and almond butter to snack on instead, and by the end of the week I have lost a couple of pounds.

Week five

The end is in sight. In order to wean myself back to normality, I am supposed to introduce alcohol in stages - just clear spirits, such as vodka, for two weeks. Once the novelty has worn off, it is much easier than it used to be to have alcohol-free evenings.

Week six

I have lost just five pounds, which seems scant recompense for six weeks' hard work. But fluid retention has gone; my skin is clearer and smoother, without flakiness, than it has been for years. My eyes look brighter. I now feel no need of coffee in the mornings. Amanda thinks I've done brilliantly.

Postscript: two months later

So, did I go out and eat a four-cheese pepperoni pizza with extra garlic bread straight away? Not quite (although it was tempting). The idea is to incorporate some of what you've learned into everyday life, which I've done: cutting out my morning latte habit, and so reducing my dairy intake to a minimum, definitely suits my skin, as does cutting out mushrooms and Marmite. Would I do it again? Definitely. But maybe not this week.

· The Balance clinic is at 250 Kings Road, London SW3 5UE. Tel: 020-7565 0333.