SEX-SPECIFIC ASSOCIATIONS OF MAGNETIC-RESONANCE IMAGING-DERIVED INTRAABDOMINAL AND SUBCUTANEOUS FAT AREAS WITH CONVENTIONAL ANTHROPOMETRIC INDEXES - THE ATHEROSCLEROSIS RISK IN COMMUNITIES

Accurate measurement of central fat patterning is difficult to obtain by conventional anthropometry. Direct measurement of intra-abdominal f at area by magnetic resonance imaging, while accurate, is impractical for large-scale observational studies. This report examines the sex-sp ecific associations of conventional anthropometric indices with intra- abdominal fat and subcutaneous fat areas measured by magnetic resonanc e imaging. A total of 157 volunteers (97 men and 60 women) aged 48-68 years of predominately white ethnicity had intra-abdominal fat and sub cutaneous fat areas measured as part of the Atherosclerosis Risk in Co mmunities (ARIC) Study. Weight, body mass index, waist circumference, waist:hip ratio, and subscapular skinfold thickness were measured or c alculated by a standardized protocol. On average, women had a lower in tra-abdominal fat area than men (109.5 cm(2) vs. 152.9 cm(2)) but a hi gher mean subcutaneous fat area (287.8 cm(2) vs. 214.6 cm(2)). After a djustment for age,intra-abdominal fat area was quadratically associate d with body mass index, waist circumference, weight, and subscapular s kinfold thickness in men; in women, these associations were best model ed by a positive linear equation. Waist:hip ratio was linearly related to intraabdominal fat area in both sexes. In general, anthropometric measures predicted lower percentages of the total variance in intra-ab dominal fat area for men than for women. For subcutaneous fat area, al l anthropometric indices were linearly associated and predicted more o f the variance in subcutaneous fat area than in intra-abdominal fat ar ea. These results indicate that among men, greater intra-abdominal fat deposition rates occur at relatively low body weights and fat is more uniformly deposited at higher weights. Women appear to deposit intra- abdominal fat at a constant rate as they gain weight, even after menop ause. The authors conclude that when waist circumference or body mass index is used as a surrogate for intra-abdominal fat area in men, a qu adratic term should be included in the analysis as a predictor variabl e, Subcutaneous fat area can be estimated well by linear measures comm only employed in epidemiologic studies.