The Action Scales Model: A Conceptual Tool to Identify Key Points for Action within Complex Adaptive Systems

James D Nobles*, Duncan Radley, Oliver T Mytton

*Corresponding author for this work

Research output: Contribution to journalReview article (Academic Journal)peer-review

15 Citations (Scopus)
466 Downloads (Pure)


Background: Systems thinking is integral to working effectively within complex systems, such as those which drive the current population levels of overweight and obesity. It is increasingly recognised that a systems approach - which corrals public, private, voluntary and community sector organisations to make their actions and efforts coherent - is necessary to address the complex drivers of obesity. Identifying, implementing and evaluating actions within complex adaptive systems is challenging, and may differ from previous approaches used in public health.

Methods: We developed the Action Scales Model (ASM) as a simple tool to help policymakers and practitioners work within complex adaptive systems to address obesity, and to help evaluators conceptualise, identify and appraise actions within such a system. The model was developed as part of the Public Health England Whole Systems Obesity programme. It aligns with, and expands upon, previous models such as the Intervention Level Framework, the Iceberg Model, and Donella Meadows’ 12 places to intervene within a system.

Results: The ASM identifies four levels (synonymous with leverage points) to intervene within a system, with deeper levels providing greater potential for changing how the system functions. Levels include events, structures, goals, and beliefs. The ASM encourages people to think differently about the systems that they work within and to identify new and potentially more impactful opportunities to leverage change.

Discussion: In this paper, we: 1) describe the rationale for the ASM; 2) present the ASM and its component parts; 3) discuss the practical utility of the ASM; 4) illustrate how stakeholders can use the ASM to evaluate actions within systems; and 5) critique the ASM alongside other available models. Whilst we use the population prevalence of obesity as an outcome of a complex adaptive system, the ASM and the associated principles can be applied to other issues.
Original languageEnglish
Number of pages10
JournalPerspectives in Public Health
Early online date15 May 2021
Publication statusPublished - 15 May 2021

Bibliographical note

Funding Information:
The authors would like to thank the 11 LAs who participated in the Whole Systems Obesity programme. Several of these LAs piloted the ASM (and other models) and provided formative feedback on its acceptability and usefulness. Their feedback helped to shape the future version of the tool. This programme was supported by Public Health England, and in conjunction with the Association for Directors of Public Health and the Local Government Association. The authors would also like to thank Professor Diane Finegood (Simon Fraser University) for her input into earlier versions of this manuscript. Throughout the time of conceptualising the ASM and writing this article, the Whole Systems Obesity team included Matthew Butler, Professor Paul Gately, Dr Katie Pickering, Jane Riley, Professor Pinki Sahota, Joanna Saunders and Dr Carol Weir. Several members of the team commented on drafts of this article (email: )

Funding Information:
The author(s) disclosed receipt of the following financial support for the research, authorship and/or publication of this article: Public Health England funded the Whole Systems Obesity programme, of which the ASM forms a part. James Nobles’ time was supported by the National Institute for Health Research (NIHR) Applied Research Collaboration West (NIHR ARC West). Oliver Mytton’s time was supported by an NIHR Clinical Lectureship at the University of Cambridge. The views expressed in this article are those of the author(s) and not necessarily those of the NIHR or the Department of Health and Social Care. The Article Processing Charge was funded through Leeds Beckett University.

Publisher Copyright:
© Royal Society for Public Health 2021.


  • complexity
  • systems science
  • leverage points
  • complex intervention
  • health policy
  • complex adaptive systems


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