Dieters have better results from joining commercial schemes like Weight Watchers and Slimming World than from receiving specialist counselling from trained GP staff.
That was the key finding into reducing obesity by the British Medical Journal which compared the success of 740 overweight men and women sent on different weight loss programmes in Birmingham.
Three groups of 124 dieters attended classes at Weight Watchers, Slimming World and Rosemary Conley respectively while the other half went on an NHS programme run by dieticians called Size Down, had one-to-one counselling at a GP or pharmacy or received one year's free entry to a local fitness centre.
After a year on the respective programmes, all bar the GP and pharmacy group achieved "significant weight loss" with those on commerically-run programmes lossing an extra 2.3kg compared to the NHS one.
One of the authors of the study, Kate Jolly, senior lecturer in public health at the University of Birmingham, said: "Commercially provided weight management services are more effective and cheaper than primary care based services led by specially trained staff, which are ineffective."
She added: "This level of weight loss [with commercial programmes] has been shown to reduce the risk of diabetes."
Yet a spokesman for the Department of Health defended the NHS programme saying: "Weight management programmes can be very cost-effective and make losing weight easier for some people, but the best way to lose weight will be different for everyone."