Achieving consensus on the language of obesity: a modified Delphi study

Background: Obesity is recognized by the World Health Organization as a chronic disease. As such, it should be referred to using the language of chronic diseases, with correct and established terminology and definitions. This study was designed to map the current language used to discuss obesity and to compare this with the standard language used for chronic disease. Methods: We performed a modified Delphi study to identify the language of chronic disease that is being used in the context of obesity, and to identify discrepancies and potential use of inadequate language with respect to the standard language used for chronic diseases. Participants (n = 24) were identified from relevant stakeholder groups and desk research, and included patients, healthcare professionals, policymakers, researchers, industry, and payers (social insurers) of 18 nationalities/regions in Europe, North/South America, and South Africa. Participants were enrolled between 20.10.2020 and 30.10.2020. The study comprised two rounds of qualitative surveys. In Round 1, participants responded to six open-ended questions. Round 2 comprised 38 statements based on key terms/themes identified in Round 1 and covered the definition, causes, progression, treatment, management, and complications of obesity. Consensus was defined as ≥70% participant agreement on a statement. Findings: All participants completed Round 1 and 23 participants completed Round 2. In Round 2, consensus was reached for 28 of the 38 statements. Participants reached a consensus regarding the use of statements that acknowledge the heterogeneous nature of obesity, but not on the use of statements that: defined obesity based on body mass index; regarded psychological, physical, or physiological factors among the main causes of obesity; or implied that weight loss should be the aim of obesity treatment. Interpretation: This study uses expert consensus to provide insight into the language used to describe obesity as a chronic disease, and forms the basis for a unified language of obesity.