Obesity is associated with insulin resistance (IR), but significant variability exists between similarly-obese individuals, pointing to qualitative characteristics of body fat as potential mediators. To test the hypothesis that obese, insulin-sensitive (IS) individuals possess adaptive adipose cell/tissue responses, we measured subcutaneous adipose cell size, insulin-suppression-of lipolysis, and regional fat responses to short-term overfeeding in BMI-matched overweight/obese individuals classified as IS or IR. At baseline, IR subjects exhibited significantly-greater visceral adipose tissue(VAT), intrahepatic lipid(IHL), plasma FFAs , adipose cell diameter, and %small adipose cells. With weight gain (3.1+1.4 kg), IR subjects demonstrated no significant change in adipose cell size, VAT, or insulin-suppression-of lipolysis, and only 8% worsening of insulin-mediated glucose uptake (IMGU).Alternatively, IS subjects demonstrated significant adipose cell enlargement, decrease in %small adipose cells, increase in VAT, IHL, lipolysis, 45% worsening of IMGU, and decreased expression of lipid metabolism genes. Smaller baseline adipose cell size and greater enlargement with weight gain predicted decline in IMGU, as did increase in IHL, VAT, and decrease in insulin-suppression-of lipolysis. Weight gain in IS humans causes maladaptive changes in adipose cells, regional fat distribution, and insulin resistance. The correlation between worsening insulin resistance and changes in adipose cell size, VAT, IHL, and insulin-suppression-of lipolysis highlight these factors as potential mediators between obesity and insulin resistance.
View details for DOI 10.2337/db15-1213
View details for Web of Science ID 000375028000015
View details for PubMedID 26884438