Jolly et al. BMC Public Health 2010, 10:439 http://www.biomedcentral.com/1471-2458/10/439 reduction in progression to diabetes of up to 58% over 4 years [5,6]. It is essential that we identify the best ways to achieve and sustain such weight loss in the general population. Douketis and colleagues [7] undertook a sys- tematic review of controlled trials of weight loss inter- ventions that had a follow-up of at least 2 years. In the trials that reported the outcomes of dietary and lifestyle therapy, a mean (sd) weight loss of 3.5 (+/- 2.4) kg was reported after 2-3 years follow-up. However, 9 of the 16 trials reported loss to follow-up rates ranging from 31- 66% and 14 trials only reported the outcomes of study completers, thus the effect of weight loss interventions were probably over-estimated. Systematic reviews have reported that combined diet and exercise interventions result in a greater weight loss than dietary interventions alone, both in the short and longer term [8,9]. Curioni and colleagues reported the outcomes at 1 year or more from 33 randomised controlled trials (RCT) of diet, exercise, or diet and exercise [9]. Mean weight loss in diet-only trials was 4.5 +/- 11.3 kg, compared to 6.7 +/- 8.3 kg in the trials of combined diet and exercise (p = 0.063). A systematic review of trials from the major commercial and self-help weight loss programmes in the USA concluded that much of the evidence was sub-opti- mal, with many lacking evidence, poor quality design and with high attrition rates [10]. Much of the research on the effectiveness of weight loss interventions has been undertaken in the USA [8]. In the UK, the effectiveness of four commercial weight loss programmes was evaluated in a publicly funded randomised controlled trial [11]. This reported that all four diets (Dr Atkins’ new diet revolution, Slim-Fast plan, Weight Watchers pure points programme and Rosemary Conley’s eat yourself slim diet and fitness plan) resulted in clinically significant weight loss (aver- age 5.9 kg) over the six months of follow-up. However, the trial excluded people with chronic medical condi- tions, such as coronary heart disease, had an upper age limit of 65 years and obtained its participants via adver- tising. This approach is likely to result in a sample that is not typical of the population trying to lose weight and targeted by primary care. By 12 months, follow-up was only 54% and many had changed diet programme. Weight loss at 12 months in those followed-up ranged from 9.0-10.9 kg in the groups to which they were ori- ginally allocated. The UK Government White paper, ‘Choosing Health’, identified inadequate provision of services for obesity [12]. This may have stimulated development of new ser- vices because a survey of 344 primary care organisations in 2004 found that 51% had set up weight management services in primary care [13]. A feasibility study of a referral service to a commercial weight management partner reported acceptable attrition rates and weight Page 2 of 8 loss in participants [14]. A primary care-based pro- gramme for obesity management in the UK, the Coun- terweight Programme, reported a clinically significant weight loss of 5% or more in 30% of attendees at 12 months [15-17]. A small pilot trial of a 12 week nurse- led programme in general practice reported a third of the intervention group achieving at least a 5% reduction in body weight compared to 20% in the usual care arm [18]. However the effectiveness of NHS weight loss ser- vices have not been compared with commercial providers. This research protocol was developed in response to a need for South Birmingham Primary Care Trust (PCT) to develop services for the management of obesity. The PCT had identified that there were insufficient weight management services available in the National Health Service (NHS) and wished to develop these. As part of this, general practitioners (GPs) had been contracted to record height and weight of their patients. One option was for GP practices or NHS pharmacies to provide weight management services, for which the PCT would reimburse these practitioners. However, in the UK, there are many well established commercial companies that provide weight management services that are widely recognised and commonly used by those seeking help to lose weight. The PCT wished to contract with services that would have a high reach, good acceptability, and showed evidence of effectiveness and cost-effectiveness. Thus the aim of this trial was to determine the effective- ness of a range of NHS and commercial weight loss pro- grammes in an unselected primary care population and to determine the characteristics of people responding to an unsolicited letter of invitation from their general practitioner. Methods/Design The study design is a randomised controlled trial with patients individually allocated to one of seven weight loss programmes: (1) Weight Watchers, (2) Slimming World, (3) Rosemary Conley (4) NHS group weight loss programme (Size Down), (5) general practice one-to-one support, (6) one-to-one pharmacist support and (7) choice of intervention; with a minimal intervention con- trol group provided with 12 vouchers enabling free entrance to a local leisure centre. Population Eligible participants are registered with general practices in South Birmingham Primary Care Trust, aged ≥ 18 years, with a raised BMI recorded within their primary care notes within the previous 15 months. The BMI threshold for invitation is that which makes them eligi- ble for primary care obesity management services within the NHS and varies according to ethnic group and the