Discrepancy Between Self-Reported and Measured Body Mass Index: A Narrative Review Protocol on Direction, Magnitude, Determinants, and Implications for Epidemiological Research and Health Policy Making

This record contains the research protocol titled "Discrepancy Between Self-Reported and Measured Body Mass Index: A Narrative Review Protocol on Direction, Magnitude, Determinants, and Implications for Epidemiological Research and Health Policy Making". The abstract of the protocol is provided below for reference. The full methodological description, workflow, and operational steps are included in the attached PDF. The DOI embedded in the document corresponds to this Zenodo record. Background: Body mass index (BMI), calculated from height and weight, remains the most widely used indicator for monitoring overweight and obesity in clinical and public health practice. Self-reported height and weight are frequently used in large-scale epidemiological surveys and surveillance systems due to their lower cost and greater feasibility. Evidence consistently shows that self-reported data are subject to systematic bias, with individuals tending to overestimate height and underestimate weight, resulting in underestimated BMI and, consequently, underestimated prevalence of overweight and obesity. The magnitude and determinants of this discrepancy remain inconsistently characterized across the literature. Objective: This protocol describes a narrative review that aims to synthesize evidence on the direction and magnitude of the discrepancy between self-reported and measured BMI, identify the demographic, somatometric, and psychosocial factors influencing this discrepancy, evaluate proposed correction methods, and discuss implications for epidemiological research and public health policy. Methods: A systematic search will be conducted in PubMed, Scopus, and Google Scholar, supplemented by backward snowballing, following a PECO-structured framework. Eligible studies will include adolescents and adults reporting both self-reported and measured anthropometric values, or evaluating correction models. Screening will be performed independently by two reviewers, with disagreements resolved by a third reviewer. Findings will be synthesized thematically, without meta-analysis or formal quality appraisal, consistent with the narrative review design and SANRA guidelines. Conclusions: The review is expected to provide an integrated account of reporting bias patterns, their determinants, and correction strategies, supporting more accurate epidemiological estimates and informing obesity-related public health policy.