The eat-everything-you-fancy diet (OK, there is a catch...)

You've never really tasted a fish pie until you've eaten it in complete silence, using chopsticks. Struggling, forkless, with chunks of salmon and haddock may seem a curious way to get to grips with lunch. But it's a surprisingly effective way to concentrate your mind on what's on your plate. The enforced slow pace makes you really taste the food, rather than wolfing it down as many of us might (ahem) tend to.

This slippery exercise is one of the tools of Beyond Chocolate, a new course designed to help women to change their relationship with food. It's not a diet and it's not aimed at anyone with a serious eating disorder. It's for women who would like to control their eating patterns rather than being controlled by them – ie most of us. The course aims to free participants to enjoy everything they like, without the compulsion to overeat. The weight loss that's likely to result is meant to be a bonus, although ironically, for many participants it will be the carrot that gets them involved.

More than half of the UK's population is now officially overweight or obese, and as the nation has ballooned, more and more of us have become obsessed with weight loss. Next Sunday the BBC launches a new 14-part nightly series, Diet Tracks, which follows 300 volunteers as they struggle to lose weight using various popular slimming regimes. The UK slimming industry is worth an estimated £2bn, and a new report by market analysts Datamonitor shows that its growth is continuing unabated. But Datamonitor's research also found that only 1 per cent of slimmers achieve permanent weight loss. Plainly, something isn't working.

The current thinking among dieticians and nutritionists is that most diets are useless. Eating no carbohydrate or stuffing yourself with fibre or insisting on pineapple at every meal simply isn't sustainable. The boring but sensible message is that the only way to maintain a normal body weight is to make lifestyle changes that can accommodate healthy eating permanently.

This is exactly the approach that Beyond Chocolate takes. It is the brainchild of Sophie Boss, 36. Sophie is not a nutritionist or a dietician. She has, however, struggled all her life with her weight, and over the years has tried every method of fat control that she could find, from slimming classes to meal replacement milk-shakes to raw-food and grape-only diets. It was when she realised that none of them worked that she decided to devise her own plan. Sophie, who is petite and vivacious, and admirably slender, spent 18 months reading up not only on nutrition but also on the psychology of eating. She has distilled the best of everything she learned into her own philosophy. Along the way, she dropped several dress sizes, lost 25lb, and, she says, learned to love her body.

The central plank of Sophie's thinking is that you can eat any damn thing you like, be it chocolate, crisps, chips or cheese – in fact, that it's good for you to eat what you want, because "forbidden foods" develop a powerful allure. This disappears when food is freely available, reasons Sophie. If you're allowed to guzzle as many Mars bars as you wish, they will lose their charm and eventually you'll be just as likely to opt for an apple when you snack. The trick, however, that lets you achieve your natural, correct body weight is to eat only because you are hungry, and stop when you are full. Harder than it sounds, of course, and this is where the Beyond Chocolate tactics come in.

Beyond Chocolate runs as either an eight-week course of evening classes, or a residential weekend course. I spent a weekend at Mickelton House, in the appropriately chocolate-box village of Mickelton in Gloucestershire. When I arrived, I was surprised and delighted to find a welcoming box of Godiva truffles on my pillow. (One of my fellow course members nervously assumed this gift was some kind of sadistic test of willpower. She left the chocs untouched until she'd been reassured that the rest of us had scoffed the lot within seconds.)

There were six of us on the course, ranging in age from twenties to sixties, and all shapes and sizes. One of the first exercises that Sophie introduced us to was actually tasting food, eating slowly, and savouring every mouthful – hence the chopstick lunch. But the only difficulty in getting it down stemmed from the eating implements. The catering at Mickelton is better than in many restaurants: this course is not about deprivation.

As well as eating too quickly, there are other barriers to eating just enough, no more, no less. We discovered that we all had a horror of wasting food, and would finish a dish rather than throw it in the bin. This wasn't confined to those among us who remembered post-war rationing; we had all been brought up to believe waste is wrong. Sophie is pragmatic about chucking away leftovers. "If you eat food when you don't want it, it's just as much wasted as if you throw it in the bin," she pointed out. "Why treat your body like a dustbin?"

Eating when you are hungry, whenever that might be, is another of Sophie's tenets, alongside not eating when you don't want to. This means forgetting about conventional mealtimes. Sophie thinks nothing of going to someone's house for dinner and saying she only wants the teeniest portion, or even warning her hostess beforehand that she doesn't want to eat. This tactic may take some working up to, though Sophie swears most people are not only receptive but also quite admiring. And when you're hungry, you should eat exactly what you want, she says. If you're in a restaurant and what you really fancy is crème brûlée, have it first, while you're keenest, then go back to the other courses if you find you then want more to eat: never mind if the waiter raises his eyebrows when he brings the starter after the pudding.

Individually, techniques like these may seem small steps (apart, perhaps, from the hairy notion of politely telling your hostess where she can stick her lasagne). But they are routes towards long-term change in one of our most fundamental, ingrained habits: eating. Changing habits and behaviour, says Sophie, who is a qualified teacher and is training as a psychotherapist, is one of the hardest things you can do: and it takes time. Rather than offering rigid rules, her course offers guidelines and ideas for developing your own individual programme: what works for one person may not be so effective for another. She remembers her own mother saying to her when she was about 12: "Darling, you'll be on a diet for the rest of your life, just like me!" No wonder she's now so pleased to be a slender size 10.

Dr Wendy Doyle of the British Dietetic Association says that the Beyond Chocolate approach is pretty much spot on; for example, she says, it takes your brain at least 10 minutes to recognise that your stomach is full, so eating slowly is a very good way to avoid consuming excess calories. It's the long-term habit-changing aspect of the course that is key, she says. "Dieticians today don't hold with banning foods or regimes you go on and off. What is needed is a lifestyle approach you can cope with over a lifetime."

Of course, the proof of the pudding is in the eating (or not). And Beyond Chocolate is a slow burn rather than a quick fix. I don't expect to turn into a Twiglet overnight. But at the very least, I've picked up some new ways of thinking and gathered some useful tools. And, who knows, they might just work. When I get back from Gloucestershire, we eat at our local pub. Do I go for the special: the home-cooked ham, double egg and chips? Nope – I think about it for a bit, and decide I'm not that hungry. I order a sandwich.

A weekend Beyond Chocolate costs £350. For more information, call 07904 125997, email sophie@beyondchocolate.co.uk, or visit www.beyondchocolate.co.uk.