Beyond Single Anthropometric Measures: Integrating Waist Circumference and Body Mass Index to Stratify Obesity-Related Health Risk.

Abstract

Purpose of the review: Waist circumference (WC) in combination with body mass index (BMI) provides unique opportunities to capture the heterogeneous nature of obesity and identify phenotypes that convey the greatest health risk. This review summarizes evidence supporting global recognition that WC and BMI should be routinely documented in health care. Differences in risk stratification when WC and BMI are used in categorical versus continuous models are examined, and strategies to increase routine measurement in clinical settings are discussed.

Recent findings: Leading authorities worldwide including the Lancet Obesity Commission and the European Association for the Study of Obesity recognize obesity as a heterogeneous condition requiring combined interpretation of WC and BMI to identify distinct phenotypes. Obesity-related risk differs substantially depending on whether WC and BMI are treated as categorical or continuous measures. Current risk stratification systems rely on categorical approaches that have clinically relevant limitations, including loss of risk resolution from applying a single WC cut-point across BMI categories. Evidence further shows that associations between WC and adverse outcomes strengthen after adjustment for BMI, and that when WC and BMI are modeled simultaneously as continuous variables, WC consistently emerges as a stronger predictor of health outcomes, while associations with BMI are attenuated or reversed. WC and BMI combined are simple tools that facilitate the identification of obesity heterogeneity and phenotypes associated with elevated health risk. Risk estimates differ depending on whether WC and BMI are modeled as categorical or continuous variables, with implications for how obesity-related risk is assessed and interpreted in practice. Recommendations for their optimal combined use, including a proof-of-concept nomogram to support clinical interpretation, are provided. Despite guideline recommendations worldwide, BMI and WC remain infrequently documented in clinical practice. This implementation gap represents a missed, low-cost opportunity to improve public health messaging, risk stratification, and clinical management of obesity-related risk.