Revisiting the obesity paradox: visceral fat distribution outperforms BMI in predicting mortality and cardiometabolic risk.
Level 3 - non-randomized controlled study
Prospective cohort analysis of nationally representative survey data (NHANES) with mortality follow-up
PubMed 41632015 · doi:10.1097/JS9.0000000000004912
What was done
Analyzed 15,925 adult participants from the 2011–2018 U.S. National Health and Nutrition Examination Survey (NHANES) using baseline cross-sectional data linked to prospective mortality follow-up. The authors examined the relationships between visceral fat index (VFI), subcutaneous fat index (SFI), VFI/SFI ratio, metabolic health status, and BMI with cardiometabolic disease (CMD) incidence and all-cause and cardiometabolic mortality.
What was found
Participants in the highest quartile of VFI had significantly higher all-cause mortality (HR 1.67; 95% CI, 1.19–2.33) and cardiometabolic mortality (HR 2.92; 95% CI, 1.44–5.93) after full adjustment. The highest quartile of the VFI/SFI ratio showed similarly elevated risks for all-cause mortality (HR 1.75; 95% CI, 1.19–2.58) and cardiometabolic mortality (HR 2.90; 95% CI, 1.42–5.90), whereas higher SFI was protective. Conversely, BMI alone showed an apparent obesity paradox, where overweight individuals had lower all-cause mortality (HR 0.74; 95% CI, 0.56–0.99) compared to normal weight. Fat distribution indices were strongly associated with CMD incidence in adults aged 45 years and older, and metabolically unhealthy status was a significant mortality risk factor, particularly in females.
Why it matters
This study demonstrates that the clinical obesity paradox observed with BMI is largely an artifact of BMI failing to distinguish harmful visceral adiposity from subcutaneous fat or lean mass. Risk stratification improves substantially when measuring abdominal fat distribution and metabolic phenotype.
Limits
Fat distribution and metabolic status were measured only at baseline, preventing evaluation of longitudinal body composition changes. The abstract does not specify the exact imaging or assessment modality used to quantify VFI and SFI, the duration of prospective follow-up, or numerical effect sizes for CMD incidence. As an observational study, residual confounding cannot be ruled out.
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