Waist Circumference Adjusted for Body Mass Index and Intra-Abdominal Fat Mass

Tina Landsvig Berentzen,Kim Overvad,Marianne Uhre Jakobsen,Riitta Parkkola,Anna Kotronen,Ronald Borra,David B Allison,Hannele Yki-Järvinen,Lars Ängquist,Thorkild I A Sørensen,Patricia Iozzo,Robert Ross,Steven B Heymsfield,Pirjo Nuutila

doi:10.1371/journal.pone.0032213

Abstract

BackgroundThe association between waist circumference (WC) and mortality is particularly strong and direct when adjusted for body mass index (BMI). One conceivable explanation for this association is that WC adjusted for BMI is a better predictor of the presumably most harmful intra-abdominal fat mass (IAFM) than WC alone. We studied the prediction of abdominal subcutaneous fat mass (ASFM) and IAFM by WC alone and by addition of BMI as an explanatory factor.Methodology/Principal FindingsWC, BMI and magnetic resonance imaging data from 742 men and women who participated in clinical studies in Canada and Finland were pooled. Total adjusted squared multiple correlation coefficients (R2) of ASFM and IAFM were calculated from multiple linear regression models with WC and BMI as explanatory variables. Mean BMI and WC of the participants in the pooled sample were 30 kg/m2 and 102 cm, respectively. WC explained 29% of the variance in ASFM and 51% of the variance in IAFM. Addition of BMI to WC added 28% to the variance explained in ASFM, but only 1% to the variance explained in IAFM. Results in subgroups stratified by study center, sex, age, obesity level and type 2 diabetes status were not systematically different.Conclusion/SignificanceThe prediction of IAFM by WC is not improved by addition of BMI.

Highlights

Several studies suggest that the association between anthropometric measures of obesity, such as body mass index (BMI) and waist circumference (WC), and mortality is U-shaped [1,2,3]
Addition of WC to BMI added 2%, 1% and 1% to the variance explained in abdominal subcutaneous fat mass (ASFM) and 40%, 17% and 27% to the variance explained in intra-abdominal fat mass (IAFM) in Canada/Turku, Helsinki/Turku and Canada/Helsinki/Turku, respectively (Table 2, crude models)
Addition of BMI to WC added 38%, 23% and 28% to the variance explained in ASFM and 2%, 0% and 1% to the variance explained in IAFM in Canada/Turku, Helsinki/Turku and Canada/Helsinki/Turku, respectively (Table 2, crude models)

Summary

Introduction

Several studies suggest that the association between anthropometric measures of obesity, such as body mass index (BMI) and waist circumference (WC), and mortality is U-shaped [1,2,3]. Recent large-scale studies have consistently shown that the association between WC and mortality is strong and direct when adjusted for BMI [1,4,5,6,7,8]. The explanation behind this direct association is not established, but one conceivable explanation is that WC adjusted for BMI is a better predictor than WC alone of intra-abdominal fat mass (IAFM), which is presumed to be the most harmful fat depot [9,10]. We studied the prediction of abdominal subcutaneous fat mass (ASFM) and IAFM by WC alone and by addition of BMI as an explanatory factor

Methods

Results

Conclusion