An association between abdominal adiposity and insulin resistance is well-established. Recent research indicates that subcutaneous fat accumulation in the lower body may be associated with higher levels of insulin sensitivity.
Hypothesis:
This pilot study tested the hypothesis that the distribution of body fat in the lower body after pregnancy is negatively associated with gestational insulin resistance.
Methods:
In 32 nulliparous pregnant women (age 27±4.5, BMI 29.5±7.9, 69% non-hispanic white), the Homeostasis Model Assessment of Insulin Resistance (HOMA-IR) was computed from fasting glucose and insulin at 24-28 weeks gestation. Body composition was assessed at mid-gestation (18-20 weeks) and at four weeks post-partum. Total body fat was estimated via bioelectrical impedance (InBody 720) and skinfold thicknesses were measured at seven sites. Dual-energy xray absorptiometry (DXA) measures of regional fat (gynoid, visceral, and leg) were obtained post-partum only. Gestational weight gain was monitored by medical records. Partial correlation analyses were controlled for age and race and then analyses were repeated controlling for baseline (mid-gestation) body fat percent. HOMA-IR was log-transformed for normality.
Results:
HOMA-IR was associated with post-partum body fat (
r
=0.45,
p
< .05) and adiposity in the trunk region (
r
=0.58, 0.57 and 0.52 for DXA visceral fat, suprailiac skinfold, and abdominal skinfold, respectively,
p
< .01), but not with gestational weight gain (
r
=.07,
p
= ns), DXA gynoid region (
r
= 0.26,
p
= ns), or any other leg measure. When analyses were further controlled for baseline body fat, post-partum measures of lower-body adiposity were strongly and negatively correlated with HOMA-IR (
r
= -0.66, -0.48, and -0.48 for thigh skinfold, DXA gynoid, and DXA leg, respectively,
p
< .05 for all). Neither DXA visceral fat (
r
= .23;
p
= ns) nor any other post-partum fat measures were associated with HOMA-IR when controlling for baseline body fat.
Conclusions:
Gestational insulin resistance was negatively associated with post-partum thigh fat accumulation, independent of overall body fat. These data indicate that insulin sensitivity may be associated with the ability to store fat in the lower body and should warrant further study of subcutaneous leg fat as a metabolically “healthy” storage depot.
Where is the beef? Waist circumference is more highly correlated with BMI and total body fat than with abdominal visceral fat in children