People referred to particular commercial weight-loss plans lost more weight than their peers involved in primary care-led weight-loss programmes, found NHS-funded research published today on bmj.com. Commercial programmes were also cheaper than primary care-based treatment, showed the Lighten Up study.

Public health and health psychology experts from the University of Birmingham, and others, investigated the relative effectiveness of different styles of weight-loss programmes provided in NHS primary care, and several commercial weight-loss plans – Weight Watchers, Slimming World, and Rosemary Conley.

The researchers recruited 740 overweight or obese men and women. They were assigned to either the control group (given vouchers for free access to their local leisure centre), or to one of seven intervention groups. These groups undertook 12 weeks’ participation in either Weight Watchers, Slimming World, Rosemary Conley, a group-base dietetics programme, one-to-one counselling in general practice or pharmacy, or their own choice of any of the six.

At 12 weeks’ follow-up, people in all intervention groups had lost a significant amount of weight. The highest mean weight loss – 4.4kg – had been achieved by the Weight Watchers group; this group also showed the best rate of attendance. At this point the mean weight loss in the general practice group was 1.4kg, which was not significantly greater than that in the control group; this programme was also the worst-attended. Allowing patients a free choice of programme did not affect their success in losing weight.

By one year’s follow-up, all groups apart from the one to one programmes in general practice and pharmacy settings – but the only group that had achieved significantly greater weight loss than controls was the Weight Watchers group.

All three commercial programmes also cost at least a third less, per participant, than either the GP- or pharmacy-led programmes.

The authors said: “Our findings suggest that a 12-week group-based dedicated programme of weight management can result in clinically useful amounts of weight loss that are sustained at one year.

“Commercially provided weight management services are more effective and cheaper than primary care based services led by specially trained staff, which are ineffective.”

Authors of a linked editorial suggest that the NHS should be wary of training its staff to manage obesity, and could learn much from commercial companies about how to deliver what consumers want.