It's a jungle out there for the overweight, with a multitude of miracle slimming programmes promising the pounds will drop off fast and easy.
Atkins vies with the Zone while bookshop shelves sag under the weight of diet tomes. Science has not offered a clear path through the confusion, beyond the odd study that has found your choice of what not to eat makes precious little difference – what matters is not to eat so much.
Today science is offering an authoritative and surprisingly positive endorsement: two studies from the Medical Research Council, led by one of Britain's leading nutrition scientists, say that Weight Watchers really does work, and is a cheap and effective way for the NHS to tackle Britain's huge obesity problem.
Dr Susan Jebb, head of nutrition and health research at the MRC's human nutrition research centre in Cambridge, is an adviser to government and a member of the Foresight team whose 2007 report warned that more than half the population would be obese by 2050, costing the nation an estimated £46bn.
She embarked on the studies because, she told the Guardian, "there is a huge pessimism among health professionals that it is just hopeless and nothing works. We know quite a lot (about what works) but we have failed to put it into practice."
She cites operations to reduce the capacity of the stomach, using gastric bands or other methods, that work "but primary care trusts are not always keen to pay the bill".
Jebb's interest in Weight Watchers is that it does not just offer another variety of diet – they are in the tricky business of behaviour change. People with a weight problem go to a weekly class, where they get help and support, as well as advice on what to eat and a way of monitoring their food intake through a points system. This sort of supportive, educative programme has been shown to work with people at risk of diabetes in the US and in Finland. The Medical Research Council, the UK's leading research body, carried out the studies but Weight Watchers paid the costs – as drug companies pay for trials of their drugs. Jebb pointed out that she has not been paid for her involvement.
There were two questions for Jebb: could Weight Watchers deliver and if they could, would it be a workable, effective answer to the obesity crisis for the NHS?
Six years ago, a few primary care trusts offered a small number of patients the chance to try Weight Watchers on the NHS. "We never marketed it to a PCT," said Zoe Hellman, WW's dietician. "Word has just spread." Two-thirds of PCTs now pay for a 12-week Weight Watchers course for some patients, at £45 a time. But it's not available to all and, until now, nobody knew what proportion of those referred was actually losing weight and keeping it off.
Jebb and colleagues carried out two pieces of work. One was an audit of the weight loss of almost 30,000 people who had been put on a 12-session course by their GP. The other was a research trial, comparing the progress over a much longer period of people who went to Weight Watchers with those who got normal care and support from their GP practice. The results of the audit, Jebb said, were impressive. These were people with a mean BMI (body mass index, which relates weight to height) of 35, which means they were technically obese. On average, the weight loss of those referred by their GP was 2.8kg (6lbs). But that average included those who went only once and some who didn't go at all. More than half – 58% – completed the course. Their average weight loss was 5.2kg and they lost at least 5% in weight. "That's the point when you can be pretty confident you will get clinical benefits," said Jebb. Even better, 12% lost more than 10% in weight.
"Our conclusion is that it works," she said. The research trial took place in Australia and Germany as well as the UK. About 800 people took part, randomised either to a Weight Watchers course or to their local health service care. This time they were followed up for a year to see whether those who lost weight kept it off. The results were also good. Although the dropout rate was high, fewer people dropped out among those who joined Weight Watchers.
Those who completed a year of Weight Watchers lost nearly 7kg, but those who were managed by their GP lost 3.9kg. About two-thirds of the Weight Watchers group lost 5% in weight, compared with one third of the others. Results were almost identical in all three countries.
Jebb said the data was "incredibly encouraging. It tells us this is an effective way of getting people to lose weight.Not only is this an effective way of losing weight, but it is very reproducible. It's the standard package (that works) - not individual group leaders." It's the support that is key, says Jebb. Zoe Hellman agrees: "One of the key things is having support and motivation. Healthy eating, getting active, helping people change their behaviour- but it is all in the context of group support," And no, she says - humiliating public weigh-ins are not part of the deal. "One of the things people bring up is the Little Britain sketch where they weigh people publicly and ring bells and talk about their weight. It couldn't be further from the truth." Only you and your group leader see what the scales say.
Jebb is excited by the findings, which she will present today at the international congress on obesity in Stockholm. But there is one big catch. "Weight Watchers and its counterparts are not going to be the kind of thing that every overweight person wants to do. Something like 90% were women. It just doesn't appeal to men," she said. She also thinks there may be other demographic issues. Weight Watchers members are also overwhelmingly white and it may appeal to some social groups more than others. But it may be possible to tailor the approach, such as by offering it via the internet.
The studies are published as the health secretary, Andrew Lansley, unveils his white paper, which will put commissioning powers into the hands of GPs. Faced with the soaring costs of treating people with obesity-related problems, such as diabetes and heart disease, GPs may well consider the £45 for 12 sessions of Weight Watchers – or a similar slimming club – to be worth trying.
