Development and stage 2 RCT with internal pilot of a weight loss maintenance intervention for obese adults after clinically significant weight loss

Obesity is a major problem worldwide, with 1 out of 4 adults being obese in the UK. Obesity is strongly related to chronic illnesses, sickness absence from work and reduced life expectancy. Weight problems costs the UK economy £16 billion a year. The NHS and the public invest considerably in weight loss treatments, but most people who are successful in losing weight quickly regain the weight they lost. Helping people not to regain weight after successful weight loss is vital in tackling the obesity epidemic.
In stage 1, we will develop a weight loss maintenance intervention for adults who were previously obese but who have lost at least 5% of their body weight in the previous 6 months. The intervention will be based on evidence from a comprehensive review of the research literature and will use techniques and theory of behaviour change which have been used in previously effective interventions. After an initial face-to-face meeting for advice and to set personal goals, participants will receive pedometers and body weighing scales which communicate data wirelessly to a central server. They will be asked to weigh themselves every day and will be prompted by text message reminder if they forgot to do so for more than one day. Weighing and weight data will be received immediately by a central server and this will trigger the delivery of automated intervention content which has been individually tailored based on the recorded weight The intervention will provide 'light touch' daily support in periods of successful weight loss maintenance, and will become more intensive of periods of weight regain.
The details of the intervention content, hardware and software will be developed in the first year using in consultation with potential users and building on the complementary expertise of our research team and the evidence from our systematic review. In addition, we will conduct a series of small pilot studies so that we can learn how to make the intervention as acceptable, possible and easy to use as possible.
In stage 2 we will recruit 288 initially obese adults after weight loss and then and randomly place them to receive either the new intervention (test) or not (a control) for six months. We will follow the participants for 12 months to test if weight regain differs between both the two groups. We will measure body weight, and other aspects related to body composition, physical activity and psychological aspects before people are allocated to each group and again 12 months later. Use of services and participant costs will be measured over the 12 month follow-up period.
To ensure that the procedures for identification/recruitment, allocation and measurement are possible and acceptable to participants we have specified a set of criteria and additional assessments based on the first three months of recruitment and first 60 participants which check if the procedures are appropriate to recruit and retain 288 trial participants within a two year period. If these pre-set targets are not met, we will consult the funder and our independent Trial Steering Committee and seek advice to either discontinue the trial or change the procedures. If the pre-set targets are met, we will continue the study and the pilot data will form part of the final trial data set. The inclusion of an internal pilot study like this provides better value for money than conducting a standalone pilot study over a relevant period for WLM and will also allow us to obtain evidence for effectiveness much more rapidly than the traditional approach of a standalone pilot would.
In addition to the standard procedures for analysing the outcomes of a randomised trial, part of the trial will be an economic evaluation which will explore the value for money of the intervention. We will also explore the relationships between socio-economic status and other participant characteristics with weight loss maintenance.

The NHS and the public invest considerably in weight loss interventions but most people regain weight rapidly. We propose developing the first WLM intervention meeting the MRC guidance for the development of complex interventions, based on evidence identified from a systematic review and configured through user-centred design. We will conduct the first UK based WLM RCT and the first such RCT conducted in Europe to recruit individuals in the community. The proposed intervention will combine automated intervention content provided through personal body weighing scales which communicate data wirelessly to a central server and tailored intervention content delivered through a mobile internet platform and personal contact. The detailed procedures of the intervention content, hardware and software will be developed in the first year using user-centred design and the evidence from our systematic review. We will conduct a series of small pilot studies to optimise acceptability and feasibility of the intervention.
We will then conduct a two-arm RCT with randomisation of 144 participants each to the new intervention or a control condition with assessment of body weight and secondary outcomes prior to randomisation and one year later. Qualitative process evaluation will be conducted with 20 participants in both groups. We will integrate an 'internal pilot' into the trial to test in the first three months and with the first 60 participants if the trial procedures are feasible. If pre-set targets are not met, we will seek advice from the funder and the independent Trial Steering Committee about either discontinuing the trial or modifying the procedures. If these targets are met, we will continue the study and the pilot data will form part of the final trial data set.
We will analyse the effectiveness and cost-effectiveness of the intervention and explore the association between socioeconomic status and other participant characteristics (e.g. age, gender, etc) with WLM.

The research on WLM support is in its infancy. To date there is very limited knowledge about effective and cost-effective means to support initially obese people after successful weight loss in preventing weight regain. While there is good evidence for the effectiveness of the drug orlistat, its costs and side effects limit widespread use. Even for people who respond well to orlistat, standard treatment involves long term behaviour change alongside medication, and evidence from behavioural WLM trials can contribute to improve treatment effects.
To date this evidence is limited and predominantly based on US trials. Very little is known about the best way to identify and reach individuals after successful weight loss through weight loss services or in communities or the best way of using current technology in delivering WLM interventions. Moreover, not a single WLM trial has been conducted in the UK seriously limiting the NHS in its capacity to manage obesity and thereby prevent morbidity and mortality. At this stage, the NHS and the public invest considerably in weight loss but the impact of this investment is limited as long term benefits will only accrue if weight loss is maintained and that rarely the case due to a lack of available evidence-based WLM interventions.
Beneficiaries include individuals and through them first and foremost the NHS and thus, the UK tax payer. Cost effective WLM interventions are a vital complement to existing services targeting weight loss and would benefit all NHS services directly and indirectly targeting obesity and coping with the consequences of obesity. These include general practice, public health and a range of services providing care people suffering from the consequences of obesity such as type 2 diabetes, heart disease, cancer, stroke, non-alcoholic fatty liver disease, Alzheimer's disease, etc. Moreover, many individuals make considerable personal investments to lose weight and the problem of the "Yo-Yo-effect" that is, people going cycles of weight loss and regain is well documented. A cost-effective evidence based WLM intervention would benefit the public by supporting proactive individuals in their efforts for maintenance of their weight loss.
The proposed intervention can be made available within two years after the completion of the project for widespread implementation and given the current lack of services for WLM at the moment, would make a considerable contribution to public health and prevention in the UK.