What makes a weight loss programme successful?
BMJ 2011One in four adults in the United Kingdom is overweight, so successful weight management programmes are urgently needed.
With about 16% of the UK population and 28% of Americans seriously trying to lose weight, it is no wonder the commercial slimming industry is booming. Although their combined reach is hard to ascertain—Rosemary Conley alone claims more than
80 000 UK members and Weight Watchers 1.5 million
worldwide members—commercial companies have their part to play.
To date, evidence of the success of commercial
approaches is limited. It could be argued that either a lot of people are trying to lose weight unsuccessfully or that without the contribution of the commercial sector the obesity crisiswould be worse. Either way, the linked trial (Lighten Up) reported by Jolly and colleagues (doi:10.1136/bmj.d6500) is awelcome addition to the evidence base.
Lighten Up was designed to test the relative effectiveness of weight management services provided by general practices, pharmacies (NHS), and commercial companies compared with a self directed exercise comparator group. The BBC’s Diet
Trials is the only other non-commercially funded study
conducted in the UK to have examined the relative efficacy of commercial weight loss programmes, and it found that all the programmes tested resulted in significant but similar weight and body fat loss compared with controls.
The Lighten Up study assessed how effectively primary care could deliver weight management services, either one to one in pharmacies or general practice or via groups (the NHS Size Down programme), compared with commercial market leaders (Weight Watchers, Rosemary Conley, and Slimming World);a further group was given a choice of programme and those in a comparator group were given vouchers to attend their local leisure centre. Only 11.5% responded to their general practitioner’s invitation to participate, most of whom were women.
Overall, Lighten Up points towards the superiority of commercial programmes in achieving weight loss. However, against the clinically relevant benchmark, the NHS Size Down and general practice groups achieved less weight rebound, with 21% and 15.7%, respectively, maintaining a 5% weight loss after one year, whereas the other groups seemed to have less success in weight maintenance. In the group given the choice of programme, men preferred the options delivered in primary care.
It is not surprising that primary care is less able to produce and deliver weight loss programmes than commercial companies, given the lack of resources compared with an industry that has spent years and invested millions to refine its products. Any intervention has a dose-response association, and the commercial sector harnesses not only the power of the group in weekly doses (sessions) but extends support via the internet, magazines, and telephone.
The intensity of the intervention itself combined with the immediacy of support (whether virtual or in real time) maintains motivation, and this combined with incentives and awards drives sustained behavioural change. In this respect,primary care models are bound to fall short of the required mark because they provide the least intensive support and the lowest dose of intervention.
The Size Down programme had eight group sessions, and although the general practice and pharmacy programmes were one to one, and presumably more tailored to individual needs, follow-up appointments were short. Weight Watchers achieved the greatest dose, with the highest proportion of participants attending more than 50% of sessions, and their participants lost the most weight after one year, suggesting that they must have the formula right.
The cost model reported in Jolly and colleagues’ paper is basic in its assumptions and limited to the cost of service provision,with primary care appearing to be more expensive than commercial programmes. Commercial companies have the size and support structure to offer consumers various packages that enhance their experience, with brand images supported by national marketing campaigns, which add value but are not costed into the service delivery model described.
These additional benefits should not be underestimated, and they set the commercial sector apart from what is likely to be viably offered by the NHS, which has to bear the real time cost of
programme delivery to very small groups compared with the commercial reach of national companies.
Qualitative studies provide some insight into what is important for consumers when trying to lose weight. The training and professional background of healthcare workers delivering primary care based weight management interventions, although well intentioned, may prevent engagement in people struggling to lose weight.
The incentive and motivation provided by
“successful slimmers,” who are often employed in thecommercial sector as “group leaders,” should not be
underestimated. The commercial sector invests in its workforce and extends supervision and training of group leaders. In the least successful programme, the NHS pharmacy one, training was limited to two days, with little assessment of staff competence and no fidelity checking of the intervention itself;
such an approach cannot compete with consumer savvy commercial programmes.
The implications of the results for primary care are that it may not seem to be equipped to compete with the commercial sector in obesity management in terms of cost and effectiveness.
Further exploration of commercial partners in weight loss would enhance the capacity of the NHS to offer weight management,with the benefit of greater choice of intervention type and style.
The bottom line in many weight loss studies, including Lighten Up, is that people have to want to change and to sustain those changes over time. Lighten Up shows that there is no simple solution to the obesity epidemic. The NHS should be mindful of the level of investment needed to develop its own expert workforce to manage complex obesity, and it can gain much information from commercial companies in how to deliver what consumers want.
