Effects of weight loss on changes in insulin sensitivity and lipid concentrations in premenopausal African American and white women

Background: Few studies have tested the hypothesis that changes in disease risk factors are more closely associated with changes in visceral fat than with changes in other adipose tissue depots, particularly in subjects with different ethnic or racial backgrounds. Objective: We describe changes in triacylglycerol, total cholesterol, HDL cholesterol, LDL cholesterol, insulin sensitivity ([S.sub.i]), visceral fat, and subcutaneous abdominal adipose tissue (SAAT) with weight loss in premenopausal, overweight [body mass index (in kg/[m.sup.2]): 27-30], African American (n = 19) and white (n = 18) women. Design: Assessments were performed before and after diet-induced weight loss to a BMI < 25. Body composition and body fat distribution were assessed with dual-energy X-ray absorptiometry and computed tomography, respectively; [S.sub.i] was assessed with an intravenous-glucose-tolerance test and minimal modeling. Results: White women lost significantly more visceral fat and less SAAT than did African American women despite similar weight losses ([approximately equal to] 13 kg). Mixed-model analysis indicated significant effects of time (ie, weight loss) on [S.sub.i], triacylglycerol, HDL cholesterol, and LDL cholesterol and of race on triacylglycerol. Time race interaction terms were not significant. After adjustment for either total body or visceral fat, time was not related to any outcome variable; however, race remained significantly related to triacylglycerol. Conclusions: With weight loss, moderately overweight African American and white women experienced significant improvements in [S.sub.i] and lipids. The beneficial effects of weight loss did not differ with race and could not be attributed to a specific body fat depot. Lower triacylglycerol concentrations among African American women are independent of both obesity status and body fat distribution. KEY WORDS Body fat distribution, intraabdominal fat, weight loss, insulin sensitivity, cholesterol, triacylglycerol, African American women, white women