Providing a common language for obesity: the European Association for the Study of Obesity obesity taxonomy

Background: The basis for a high-performing and resilient healthcare system is having a common, precise, and scientifically accurate language used across all stakeholder groups. However, such a common language is lacking for obesity. Therefore, the European Association for the Study of Obesity undertook a taxonomy initiative to provide standardised language for obesity as commonly used from policy to practice for other major policy-prioritised non-communicable diseases (NCDs). Methods: An online Delphi consensus study was conducted, involving a panel of experts representing stakeholder groups of policymakers, healthcare professionals, people with lived experience, and researchers. Based on the understanding of obesity as an adiposity-based chronic disease, 54 statements demarcated into definition, scope and contextual usage were developed across six themes: Definition of obesity, Causes, onset and progression, Obesity prevention, Screening and early diagnosis, Treatment and management, Obesity consequences. Results: Of the 194 invited experts, 70 (36%), 63 (33%), and 58 (30%) experts participated in rounds one, two, and three, respectively. Consensus was achieved on 70% of the proposed definitions, scope, and contextual usage after round one, 94% after round two and 100% after round three. The Definition of Obesity theme included distinctions between population-level indicators and individual-level signs of obesity, and how pre-obesity was defined. The Causes, Onset and Progression theme characterised the timing of obesity development. The Obesity Prevention theme explicitly differentiated between health promotion and primary prevention. Both the Screening and Early Diagnosis, and the Treatment and Management themes defined concepts supporting a continuum of care model. The Consequences of Obesity theme encompassed health and socio-economic outcomes. Conclusion: The taxonomy provides a contemporary evidence-based language about obesity that aligns with language used for policy-prioritised NCDs. The taxonomy is useful for education, advocacy, and communication and can be used by policymakers, healthcare professionals, people living with obesity, researchers, and health system users.