Don't let festive spirits make mincemeat of your diet

'Temptation]' cries Angeline, who is addressing an early evening meeting at a Baptist hall in south London. 'Temptation brought us here. Every single one of us.'

Angeline is standing in front of a group of about 30 women, ranging in age from their late teens to early sixties. Some look inspired by her words, others apprehensive. A handful of young children entwine themselves around their mothers' legs, bored, restless, wheedling for drinks.

'You can't get a drink here,' says Ellen, a 30-year-old single mother. 'There's nobody in the kitchen.'

Veronica, 31, is frightened. 'It's the downtime,' she says. 'The boredom. It's just that long weekend I'm particularly worried about. Just sitting around, not doing anything.' Angeline is reassuring: 'Whatever happens,' she says, 'you can always come back in the new year.'

Veronica nods: she'll be back, along with 30 new members. For this is not the Jesus Army women's section but a pre-Christmas meeting of Weight Watchers. There is a lot of sensible talk about 'allowing yourself to go up three pounds'. The seasonal advice sheets contain some handy hints: 'Why not take a short break from the hectic Christmas preparations and enjoy a 10- minute walk each day?' or, 'ask yourself, do you really want that extra roast potato or that second slice of Christmas cake?'

But panic is in the air. As Angeline reminds us, a glass of wine has 100 calories; a single peanut has eight. The Weight Watchers Hotline as given in the phone book reports: 'The number you have dialled has not been recognised. Please redial and try again.' There is anxious talk about gate-crashing the Tooting meeting later in the week.

What's your weakness? I ask Cindy, who is 53. 'Food,' she says. 'I'm not greedy, I don't eat cakes or anything. I eat fish, meat, chips - it's all food. I like food. Always hungry. Food always in my mind.' Cindy is from Portugal. 'We don't have mince pies. We have fried bread with sugar and cinnamon and wine. It's very fattening. It's worse than Christmas pudding. I like it.'

Beth, 23, has lost seven and a half pounds. 'I don't like the idea of stuffing myself. It's the alcohol that will be a problem. I'm going to count it from my optional calories and stay away from chocolate.' 'Lying cow,' says her sister, Ellen. 'She's five inches taller than me. And younger. And she hasn't got kids. I wasn't as overweight as she is when I was 23.'

The big success story - apart from Angeline who, like all group leaders, has lost weight the Weight Watchers way - is Mandy, 27, who has lost five stone in seven months. 'Last year I ate everything in sight,' she says. 'Everything that passed I had to eat. It's force of habit. You just sit there and eat till you can't move. This year it's all planned.' She reels off her two-day menu plan, including suet-free Christmas cake.

The recipes come from a Weight Watchers' recipe book, of which there are several. The organisation is a merchandising dream: tonight Angeline is plugging Chocolate Options drinks ('Only 40 calories - count them]') and the brand new workout video. Members are warned not to buy the fake American import. She is also presenting a gold tick to Ann-Marie, who has lost seven pounds. 'Well done]' says Angeline.

There are other motivating factors: pretty Filofaxes, useful jargon. ('They call it a food plan, not a diet,' says Mandy.) 'And you pay a lot of money to come here and be weighed - pounds 3.80 a week,' says Deidre, 57. 'You've got to stick to the plan.'

The meeting - weigh-in, pep talk, confessions - has the air not of boxers psyching up for the coming fight, but a consciousness-raising group. At one point, the conversation drifts into how men never wash up at Christmas. A solitary young man, dressed in army fatigues, was waiting anxiously in the hall when I arrived; he scuttled off immediately after the weigh-in.

Meanwhile, it's back to Angeline, trim as a pin in a black dress, high shoes, shocking pink jacket. 'Christmas is not just about food, is it?' she says. 'But you know what it's like. All those little extras you pick up at Sainsbury's, just in case. Those dangerous foods for people that never come around. Who leaves their house on Christmas day?

'What are you going to drink? Water's not very Christmassy, is it. Tonic water? That's better. You could stick a lemon in it. It sounds like it's not much, but on the day it's things like that that keep you going.'

'Mummy]' interrupts one of the kids. 'Got any chocolate?' 'He doesn't eat chocolate,' says Mandy. 'Yes I do.'

Miles Kington is on holiday.