The researchers, who have already carried out a clinical trial to compare a range of weight management programmes with free leisure centre vouchers, were previously unable to directly compare the effectiveness of the main UK commercial programmes. Evidence of effectiveness of Weight Watchers has been shown in three previous trials. The researchers set out to observe whether two other commercial services - Slimming World and Rosemary Conley – were inferior to Weight Watchers, and found that they were not
They also showed that an NHS weight loss programme, compared in the same observational study, produced significantly less weight loss after three months.
In the new study, 3,290 overweight patients were offered a choice of free weight loss programme from several and had their weight loss recorded at three and 12 months later, before comparing them against Weight Watchers. The trial was designed to discover if any programmes were inferior to Weight Watchers – and found that only the NHS programme was.
Participants were recruited from the Lighten Up weight management service commissioned by South Birmingham Primary Care Trust, and invited to participate by their GP. The criteria for inclusion including being over 18 and with a raised body mass index.
After three months, the Weight Watchers group had lost an average of 4.2kg, Slimming World participants had lost an average of 4kg and Rosemary Conley, an average of 3.3kg. However, those who chose to take part in the NHS programme had only lost an average of 1.6kg.
And although the weight losses converged for the groups at 12 months, the NHS programme was still the least successful, with an average loss of 2.5kg, compared to 3.7kg for WeightWatchers, 3.1kg for Rosemary Conley and 4.5kg for Slimming World.
The researchers said that the findings showed that practical differences between the three commercial programmes were small and that all three should be commissioned by public health providers, giving a greater amount of personal choice to patients which, they said, should extend take-up of the services.
Claire Madigan, from the School of Health and Population Sciences at the University of Birmingham, who led the study, said: “This research will provide really useful information for commissioners of weight management services, essentially that commercial programmes result in similar weight losses and in this case result in more weight loss than an NHS programme. ”
The study What weight loss programmes are as effective as Weight Watchers: non-inferiority analysis is published in the British Journal of General Practice today (Saturday).