Body fat distribution and cardiovascular risk in normal weight women. Associations with insulin resistance, lipids and plasma leptin

OBJECTIVE: To systematically examine the correlations between insulin resistance, plasma leptin concentration, obesity and the distribution of fat assessed by anthropometry and magnetic resonance imaging in Asian women. DESIGN: A cross sectional study of non-diabetic, normal weight women. SUBJECTS: Twenty-one healthy women aged 38.8 y (s.d. 11.7) and BMI 22.6 kg/m(2) (s.d, 2.3). MEASUREMENTS: Intraperitoneal, retroperitoneal and subcutaneous abdominal fat volume was assessed by magnetic resonance imaging. Anthropometric data were collected. Total fat mass was assessed by bioelectric impedance analysis. Easting serum lipids, insulin and plasma leptin were assayed. RESULTS: Generalized obesity correlated with subcutaneous abdominal fat mass (r = 0.83, P < 0.001), but not with intra-abdominal fat mass. Both intraperitoneal fat mass and retroperitoneal fat mass increased with age (r = 0.58, P = 0.005 and r = 0.612, P = 0.003, respectively). Abdominal subcutaneous fat mass was the most important determinant of insulin resistance and plasma leptin, Of the serum lipids, only fasting triglyceride correlated significantly with the waist-to-hip ratio. CONCLUSIONS: It is possible that the large size of the subcutaneous depot compared to the intra-abdominal depot overwhelms any metabolic differences between adipose tissue from these two sites, resulting in the stronger correlation between insulin resistance and subcutaneous abdominal fat mass rather than intra-abdominal fat mass. On the other hand, the distribution of fat between subcutaneous fat depots may be important in the metabolic syndrome given the correlation of fasting triglyceride with waist to hip ratio but not with abdominal fat. However, the study population was small, younger and leaner compared to previous studies and we may not be able to generalize these results to all segments of the population. We confirm that subcutaneous fat mass is the major determinant of plasma leptin.