1 October 2018 - 28 February 2022
Approaching evaluations of public health interventions to tackle obesity from a complex systems perspective

Project summary
My PhD project aims to develop and use systems theory to describe the complexity of the public health dietary behaviour and obesity system in relation to commercial food systems. In doing so, it aims to further develop a sub-system and quantitatively capture its actors and interconnections in a dynamic system, which in turn can be used to assess different policy scenarios. This aim will be achieved through the following objectives:
• Carrying out a systematic review to define what are the commercial determinants of obesity in adolescence, develop a framework by which these factors can be operationalised and quantified.
• Carrying out systems mapping workshops – using a Group Model Building approach – with stakeholders (adolescents, academics and policymakers) to develop system maps where commercial activities, that have an influence on dietary behaviour and obesity in adolescence, will be identified by the different stakeholders. These different maps will be discussed (to find similarities and differences between them) and finally merged into one that represents stakeholders’ views.
• Using a system dynamic modelling methodology, the map developed in the previous phase will be quantified and will be used to model different policy scenarios for assessment and comparison of intended and unintended impacts.
Practice engagement
The progress of my project has been shared with practice partners Claire McIver, [Public Health Consultant in Staffordshire County Council], James Nobles [Senior Research Associate CLAHRC West], and the advisory group (Prof Martin White and Prof Steven Cummins) to receive feedback and improve methodology as well as double-checking relevance of the project. I’ve presented the progress of my project in academic seminars and postgraduate courses at the Medical School and School for Policy Studies, and presented academic posters at the Annual Scientific Meeting SPHR in Newcastle 2019 and at the International Society for Behavioural Nutrition and Physical Activity in Prague; in 2020 I was an invited speaker to present results from my first PhD study at a Department of Public Health monthly meeting in the MRC Epidemiology Unit, University of Cambridge .
Public engagement
Study 2 in my PhD (Systems mapping workshops) is being co-created with adolescents, policymakers and academics in order to be used in a policy setting and test obesity prevention strategies. I’ve been engaging with Claire McIver, James Nobles, Michael Bell [Patient & Public Involvement Facilitator for NIHR ARC West], Bristol Young Person’s Advisory Group (YPAG) and with 9 community youth-groups in the South West of England to plan, engage and develop the workshops.
Dissemination: Results from the mapping workshops will be shared with the stakeholders to refine and validate them. Findings from this study will be published in peer-reviewed journals and presented at relevant conferences. A policy briefing will be written for the Policy Bristol blog.
Publications
Chavez-Ugalde, Y., Jago, R., Toumpakari, Z., Egan, M., de Vocht, F. (2019) Defining the commercial determinants of obesity in adolescence: a systematic review protocol. PROSPERO. CRD42019137363
Chavez-Ugalde, Y., Jago, R., Toumpakari, Z., Egan, M., Cummins, S., White, M., Hulls, P., de Vocht, F. (2020) Defining the commercial determinants of dietary behaviours associated with obesity, in the general population and in adolescents: systematic review and development of a theoretical framework. IJBNPA
Chavez‑Ugalde, Y., Toumpakari. Z., White, M., De Vocht, F., Jago, R. (2022). Using group model building to frame the commercial determinants of dietary behaviour in adolescence – proposed methods for online system mapping workshops. BMC Medical Research Methodology. 22(84).
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