Abstract MP50: Fat Distribution and Metabolic Health: Central and Lower Body Adipose Tissue Depots are Differentially Associated with Insulin Sensitivity in Parous and Nulliparous Caucasian and African American Women
Parity and race individually affect the accumulation of visceral adipose tissue, but their combined influence on the relationship between fat distribution and insulin sensitivity is unknown. The purpose of this study is to test the influence of parity and race in the relationship between insulin sensitivity and the preference of central versus lower-body fat accumulation in overweight women.
METHODS: In non-Hispanic white (white; n= 109, 56 parous) and African American (AA; n= 119, 58 parous) pre-menopausal women matched for age and BMI (age 34 ± 6.2; BMI = 27.5 ± 4.7), intra-abdominal adipose tissue (IAAT) via CT, regional and total body fat by DXA, insulin sensitivity (SI) calculated from minimal model, and cardiorespiratory fitness (VO2max) were assessed.
RESULTS: Nulliparous women (NP) were younger (31.3 ± 6.5 vs 36.4 ± 5.1), had less IAAT (69.6 ± 31.4 vs 85.4 ± 30.3), and a higher VO2max (29.5 ± 4.0 vs 27.7 ± 3.6), but showed no difference in SI or leg fat compared to parous women. Stratified by race, white women were more insulin sensitive (3.5 ± 1.8 vs 2.5 ± 1.9 [x 10-4 min-1/(μIU/ml)]), had a higher VO2max (29.2±4.0 vs 27.6±3.6), and more IAAT (92.7±30.4 vs 65.1 ± 25.9) than AA women, but less leg fat (26.6 ± 3.7 vs 28.2 ± 3.1).
IAAT is negatively related to SI in NP (r= -.40, p< .001), but not in parous (r= -.15, p= .16), when controlled for age and body fat. This relationship is particularly strong in white NP (r= -.58, p< .001), but not in AA NP (r = -.24, p = .13), white parous (r= -.24, p= .09), or AA parous (r= -.18, p= .24). These relationships remain robust whether analyses are controlled for total body fat mass, leg fat, and/or VO2max. Leg fat is positively related to SI in both NP (r= .45, p< .001) and parous (r= .25, p< .05). Stratified by race, this relationship remains strong in all groups (r> .4, p< .01), except parous AA women (r= .17, p= .26).
Multiple linear regression indicates that IAAT, age, leg fat, race, and VO2max are independent predictors of SI in NP. In parous women, only race achieved significance. IAAT, age, leg fat, and VO2max are predictors of SI in white NP, but not in white parous. Leg fat is the sole predictor of SI in AA NP, while none of the variables are significant in AA parous.
CONCLUSION: These data demonstrate that the relationship between fat distribution and insulin sensitivity in overweight women varies as a result of race and reproductive history. In NP, the more insulin sensitive the individual is, the more fat accumulates in the legs and the less it accumulates in the abdomen. Race clearly influences these relationships. The SI/abdominal fat relationship is more pronounced in white women, while SI/leg fat predominates in AA. SI loses its strong association with abdominal obesity in white parous women and its association with leg fat in AA parous women. This dissociation suggests that both hepatic metabolism and fat distribution are altered by high hormones during pregnancy in both racial groups.
Author Disclosures: K.H. Ingram: None. G.R. Hunter: None. B.A. Gower: None.
- © 2015 by American Heart Association, Inc.