Lower Extremity Fat Mass Is Associated With Insulin Resistance in Overweight and Obese Individuals: The CARDIA Study

Abstract

Lower extremity fat mass (LEFM) has been shown to be favorably associated with glucose metabolism. However, it is not clear whether this relationship is similar across varying levels of obesity. We hypothesized that lower amounts of LEFM is associated with higher insulin resistance (IR) and this association may vary according to weight status. Participants with available measures were examined from the Coronary Artery Risk Development in Young Adults study (CARDIA), a multi-center longitudinal study of the etiology of atherosclerosis in black and white men and women aged 38–50 years old in 2005–2006 (n = 1,579). The homeostasis model assessment of IR (HOMAIR) was calculated to estimate IR, regional adiposity was measured using dual energy X-ray absorptiometry (DXA), and weight status was defined according to BMI categories. Obese and overweight participants exhibited higher IR, total fat mass (FM), trunk FM (TFM), and LEFM compared to normal weight participants. After controlling for age, height, race, study center, education, smoking, and cardiorespiratory fitness (CRF), greater LEFM was significantly associated with higher IR only in normal weight men and women. Further adjustment for TFM revealed that lower LEFM was significantly associated with higher IR in overweight and obese men and women and the positive association in normal weight individuals was attenuated. These results suggest that excess adiposity in the lower extremities may attenuate the metabolic risk observed at a given level of abdominal adiposity in overweight and obese individuals. Weight status presents additional complexity since the metabolic influence of adipose tissue may not be homogenous across anatomic regions or level of obesity.

The Role of Adipose Tissue in Insulin Resistance in Women of African Ancestry

“…Traditionally one of the major determinants of insulin resistance is the centralization of body fat [9], more specifically increased visceral adipose tissue (VAT) [10], while peripheral (glutealfemoral) subcutaneous adipose tissue (SAT) deposition has been shown to be “protective” against insulin resistance (in predominately white populations) [11]. Yet, many studies in South Africa and the USA have shown that at the same level of BMI or waist circumference, black women are more insulin resistant than their white counterparts, despite having less VAT [4–6].…”

Intermuscular and intramuscular adipose tissues: Bad vs. good adipose tissues

“…2,[15][16][17][18][19][20][21][22][23] However, this message is further muddied by new reports that demonstrate that truncal SQF adipose tissue may actually aid in the metabolic changes that occur with obesity as this depot supplies a greater percentage of adipose tissue compared with the VAT and that the protective effects of SQ fat is limited more to the gluteal femoral SQ depot (or the so-called "pear-shape"). 11,15,[24][25][26][27][28] The protective action of gluteal femoral SQF seems to be further limited to the femoral subcutaneous region and not necessarily with the gluteal region in black South African women further confounding the issue with ethnicity differences. 11,16,25,27,[29][30][31][32] Indeed, even gender appears to have a profound influence on the responses by different adipose depots.…”

Intrauterine protein restriction combined with early postnatal overfeeding was not associated with adult-onset obesity but produced glucose intolerance by pancreatic dysfunction

“…Insulin resistance and metabolic syndrome are established consequences of expanding visceral fat mass [9], whereas the expansion of subcutaneous fat is associated with improved glucose tolerance and a lower risk of developing obesity related co-morbidities [10,11]. Moreover, recent studies have shown that higher gluteofemoral fat mass is associated with protection against insulin resistance in obese men and women [12,13]. The protective role of gluteofemoral body fat results from its distinct properties with regard to lipolysis and fatty acid uptake [14].…”