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Feasibility study: incentive interventions for weight loss to inform future effectiveness and cost-effectiveness trial

Feasibility study of how to best engage obese men in narrative SMS (short message system)


To co-produce with PPI, an acceptable and feasible RCT design with broad reach to test a narrative theory-based SMS intervention with embedded BCTs, with and without an endowment incentive, compared to waiting list control, to inform a future full trial.


Phase 1: intervention adaptation

  1. To collaborate with a charity for men and obese men to minimise inequalities and maximise intervention appeal and reach.
  2. To refine the theoretical basis of the intervention by integrating systematic review findings and NICE evidence for reducing diets, PA, BCTs and theory to refine a logic model.
  3. To operationalise acceptable and effective BCTs to embed in a novel narrative SMS delivery form, which builds on existing NIHR-funded narrative SMS alcohol interventions.
  4. To identify acceptable ways to provide a menu of information resources on e.g. diet, PA, visual feedback of self-report weight and waist circumference, pedometer readings using our own or other available open source websites.
  5. To optimise an endowment incentive in order to motivate behaviour change. This will be achieved through applying insights from behavioural economics and a survey/DCE with obese men to define the frequency, constant or varying values and contingency of incentives on targets met for i) initial weight loss ii) weight loss maintenance.
  6. To select acceptable and valid outcome and cost-effectiveness measures with potential for future long-term data linkage.
  7. To produce a library of SMS content, recruitment materials and a Phase 2 protocol.

Phase 2: feasibility trial to refine approach, recruitment, randomisation, intervention delivery, engagement, retention and follow-up processes

  1. To assess the acceptability and willingness to be randomised to i) SMS ii) SMS and endowment incentive or iii) waiting list for SMS.
  2. To assess the acceptability and feasibility of recruiting from GP practice obesity registers and community venues, identified in Phase 1.
  3. To determine the acceptability of intervention content, delivery and attendance levels for objective weight measures at baseline, 3, 6, and 12 months and any unintended consequences.
  4. To assess the likely impact on % weight loss at 12 months and health inequalities via assessment of differential uptake and potential effectiveness by socio-economic group


In the UK 25% of people are obese, with higher prevalence in men and those from deprived backgrounds. Obesity conveys an increased risk of serious health conditions and is a major public health priority. This novel narrative SMS and endowment incentive feasibility study fit the NICE research recommendations to investigate new technologies and specific behaviour change techniques.  It builds on Unit work by Pat Hoddinott on the NIHR funded ROMEO systematic reviews on obesity in men [HBC01.6] and on incentive interventions for health-related behaviour change [HBC02.1].  It also builds on the PhD undertaken by Mark Grindle, who has a background in film, television and computer games script writing and production (graduated 2014, University of Stirling) entitled: The power of digital storytelling to influence human behaviour. Mark’s PhD was supervised by the Unit’s Brian Williams.  The study also builds on learning gained by Brian Williams and the Dundee collaborators on delivering SMS interventions to men with alcohol problems [HBC01.3 HBC01.7, HBC01.8]

The Game of Stones study is collaborating with the Men’s Health Forum, who also provided Patient and Public Involvement (PPI) in the ROMEO study [HBC01.6]  Additional PPI and qualitative research has been undertaken with men in the target population via community groups like Men’s Sheds to refine the design of the intervention and trial processes.  A survey and a Discrete Choice Experiment (DCE) informs the design of a feasibility RCT which has three arms: narrative SMS, narrative SMS with financial incentives linked to target weight loss, a waiting list for the SMS intervention (control).  Men are followed up at 3, 6 and 12 months.  A University of Stirling PhD student, Rebecca Skinner, supervised by Pat Hoddinott will follow up men for a further year after the study has finished investigating their experiences with weight management.


The survey and DCE were completed by a representative UK sample of 1044 obese men.  The feasibility RCT is in progress and met the pre-specified recruitment target of recruiting 105 obese men within 4 months at 2 sites using two strategies; obese men registered at GP practices and through community venues. The sample includes more men from disadvantaged backgrounds than most other obesity intervention studies.

Principal Investigator: Professor Pat Hoddinott

NMAHP Research Unit Collaborators: Andrew Elders

External Collaborators: Grindle M - University of Stirling, Avenell A - University of Aberdeen, Gray C - University of Glasgow, Jones C - University of Dundee, Kee F - Queens University Belfast, Men's Health Forum Charity, McKinley M - Queens University Belfast, van der Pol M - University of Aberdeen

Funder: NIHR/PHR

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