Designing, delivering, and evaluating novel interventions to support dietary change for weight management

Abstract

Background: Recent empirical research and theoretical models acknowledge that impulsive processes, can often undermine peoples’ attempts to lose weight despite currently available and effective support (Chapter 2). Aim: To develop, deliver, and evaluate an impulse management intervention to support weight loss in adults. Methods: A systematic review was conducted to identify available impulse management techniques for influencing eating behaviour (Chapter 3). Intervention Mapping was used to develop the intervention (Chapter 4) which drew on various sources including the findings from the systematic review, stakeholder consultations, existing guidance, and qualitative interviews. A two-arm randomised controlled feasibility trial (Chapter 5), with nested mixed-methods process evaluation and two cycles of intervention delivery and data collection (Chapter 6), was conducted. This assessed the feasibility and acceptability of, and informed refinements to, both the intervention and trial procedures in preparation for a full-scale effectiveness evaluation. Weight was measured as the proposed primary outcome for a full-scale trial at baseline, one-month, and three-months of follow-up, app usage data were collected at both follow-up time points, and semi-structured interviews were conducted at one-month with a subsample of intervention group participants only. Results: The systematic review critically appraised and synthesised evidence on 17 identified techniques which were categorised as Impulse-focused or Reflective techniques. Promising changes in eating behaviour and craving were found for the techniques of visuospatial loading, physical activity, and implementation intentions. Intervention Mapping resulted in development of a novel smartphone app-based intervention (ImpulsePal) aimed to reduce unhealthy snacking, overeating, and alcoholic and sugary drink consumption using impulse management techniques identified in the systematic review. Eighty-eight adults with a Body Mass Index of ≥25kg/m2 and wishing to lose weight, were recruited and randomised in a 2:1 ratio to use ImpulsePal (n=58) or to a waiting list control (n=30) group. Data were available for 74 participants (84%) at one-month and 67 (76%) at three months. Exploratory analyses suggest that the ImpulsePal group (n=43) lost 1.03kg (95% CI 0.33 to 1.74) more than controls (n=26) at one-month, and 1.01kg (95% CI -0.45 to 2.47) more at three months. Participants reported high satisfaction with the intervention and trial procedures. The process evaluation suggests that ImpulsePal and the impulse management techniques are feasible to deliver and acceptable to users. Interviews with twenty-two participants suggest that they valued having access to in-the-moment support, felt more aware of their own eating behaviour and influences on it, and felt an increased ability to resist temptations. Conclusions: This work has developed a novel, theory- and evidence-informed, person-centred app which showed potential to improve impulse management, promote healthier eating, and support weight loss. ImpulsePal is acceptable to overweight and obese adults who want to lose weight and is now ready for evaluation in a full-scale trial. The thesis discusses theoretical, methodological, and practical implications for the future development, evaluation, and implementation of digital behaviour change interventions.