Barbara J. Nicklas

Adiponectin levels do not change with moderate dietary induced weight loss and exercise in obese postmenopausal women

OBJECTIVE: The purpose of this study was to determine changes in adiponectin levels with moderate weight loss, weight loss plus aerobic exercise, or weight loss plus resistive exercise in overweight and obese, sedentary postmenopausal women.DESIGN: Longitudinal, clinical intervention study of 6-month (3 × /week) program of either weight loss (WL, n=15), weight loss + aerobic exercise (WL+AEX, n=16), or weight loss + resistive exercise (WL+RT, n=9)SUBJECTS: We studied 40 sedentary, overweight and obese (body mass index, BMI=32±1 kg/m2, X±s.e.m.) postmenopausal (57±1y) women.MEASUREMENTS: Fat mass and fat-free mass (FFM) by dual-energy X-ray absorptiometry, plasma insulin, leptin, and adiponectin by radioimmunoassay.RESULTS: Age, body weight, BMI, waist and hip circumferences, waist-to-hip ratio, VO2max, percent fat, total body fat mass, FFM, and fasting plasma glucose, insulin, leptin, and adiponectin concentrations were similar among WL, WL+AEX, and WL+RT groups before the interventions. In all women combined, body weight, BMI, and waist and hip circumferences decreased (P < 0.001). There was a significant absolute decrease in percent body fat from 47 to 44%, representing a 13% decrease in total fat mass and a −1.6% change in FFM. Fasting concentrations of plasma adiponectin did not change (40±16%, P=NS), whereas fasting plasma glucose, insulin, and leptin all decreased (P<0.001).CONCLUSIONS: Plasma adiponectin levels do not change with a 6-month moderate weight reduction program even when accompanied by aerobic or resistive exercise training in overweight and obese postmenopausal women.

Daily Energy Expenditure Is Related to Plasma Leptin Concentrations in Older African-American Women but Not Men

Recent research suggests that leptin may control body weight by regulating energy expenditure and energy intake in mice. To explore the possible role of leptin in the regulation of energy expenditure in humans, we used doubly-labeled water methodology to determine whether fasting plasma leptin concentrations were related to total daily energy expenditure (TEE) and its components, resting energy expenditure (REE) and physical activity energy expenditure (PAEE), in free-living older African-American men (n = 21) and women (n = 25). Plasma leptin concentrations were higher in women than men, even after the adjustment for differences in fat mass (28 ± 3 ng/ml for women vs. 17 ± 3 ng/ml for men; P < 0.01). The logarithm of plasma leptin concentrations correlated with fat mass in both women (r = 0.80) and men (r = 0.78) (P < 0.0001). After statistical adjustment for sex differences in fat-free mass and fat mass, women had lower TEE (22%) and REE (15%) (P < 0.01) and a trend (P = 0.08) toward lower PAEE, compared with men. After controlling for the effects of fat-free mass on energy expenditure, plasma leptin concentrations were related to REE (r = 0.68, P < 0.001) and tended to be related to TEE (r = 0.37, P = 0.07) in African-American women but not men (r = 0.18 and −0.03, respectively). Plasma leptin concentrations were not related to PAEE in either men or women. These results suggest that leptin may contribute to the regulation of TEE in older African-American women through its effects on resting energy metabolism, but the role of leptin in the regulation of energy expenditure is less apparent in older African-American men.

Aerobic exercise is necessary to improve glucose utilization with moderate weight loss in women

Objective: To determine the effects of weight loss (WL) alone and combined with aerobic exercise on visceral adipose tissue (VAT), intramuscular fat, insulin‐stimulated glucose uptake, and the rate of decline in free fatty acid (FFA) concentrations during hyperinsulinemia.

Dietary intake and changes in lipoprotein lipids in obese, postmenopausal women placed on an American Heart Association Step 1 diet

BACKGROUND Dietary intake and changes in lipoprotein lipids in obese, postmenopausal women placed on an American Heart Association Step 1 diet. OBJECTIVE The purpose of this study was to determine the specific dietary factors associated with the commonly observed decrease in HDL-C concentration in obese, postmenopausal women placed on a low-fat diet. DESIGN/SUBJECTS/INTERVENTION: Dietary intake, lipoprotein lipid concentrations, and body weight were measured before and after 10 weeks of instruction in the principles of the American Heart Association (AHA) Step 1 diet in 55 overweight and obese (body mass index=33+/-4 kg/m2), sedentary, postmenopausal women (mean age 59+/-5 years). RESULTS The percent of energy obtained from total fat, monounsaturated, polyunsaturated, saturated fat, and dietary cholesterol decreased significantly after dietary intervention, while the polyunsaturated:saturated ratio and the percent of energy obtained from total carbohydrate, complex carbohydrate, and simple carbohydrate increased. On average, the women lost a small, but significant, amount of body weight (2%+/-3%, P<.0001). Adherence to the AHA diet reduced total cholesterol (-8%+/-8%), LDL-C (-6%+/-11%), and HDL-C (-16%+/-10%). The only dietary change that predicted decreases in HDL-C concentrations was the increase in the percent of energy from simple sugar (r=-0.32, P<.05). There were no relationships between changes in HDL-C and changes in percent of energy from fat (r=0.16), saturated fat (r=0.07), polyunsaturated fat (r=0.04), or monounsaturated fat (r=0.09). APPLICATIONS/CONCLUSIONS In postmenopausal women, a dietary reduction in total fat, saturated fat, and cholesterol reduces body weight, total cholesterol, and LDL-C, but substitution of simple sugar for dietary fat may lead to a reduction in HDL-C. Further research is needed to determine which specific simple sugars are contributing to diet-induced reductions in HDL-C in older women placed on a low-fat diet.

Lipoprotein subfractions in women athletes: effects of age, visceral obesity and aerobic fitness

OBJECTIVE: To examine whether lipoprotein subfractions are associated with age-related changes in visceral obesity and maximal aerobic fitness in women athletes.SUBJECTS AND MEASUREMENTS: Body composition was measured using dual energy X-ray absorptiometry (DEXA) and a single slice computed tomography (CT) scan of the abdomen of 39 women athletes (age: 18–69 y, body mass index (BMI): 19–24 kg/m2). Lipoprotein lipids were measured in plasma drawn after a 12 h fast using nuclear magnetic resonance (NMR) spectroscopy, which quantifies lipoprotein subfractions by the spectroscopic differences exhibited by lipoprotein particles of various sizes.RESULTS: Total cholesterol (r=0.42; P<0.01) and low-density lipoprotein cholesterol (LDL-C) (r=0.32; P=0.05) correlated positively with age, even after adjustment for age-related decreases in maximal aerobic fitness (VO2 max) and increases in the intra-abdominal fat area. There were no relationships between any of the lipoprotein subfractions or sizes with age. Very-low-density lipoprotein (VLDL) size and VLDL2-TG correlated with total fat mass (r=0.40 and r=−0.43, respectively; P<0.05) and with intra-abdominal fat area (r=−0.47 and r=0.43, respectively; P<0.01), but not independently of total fat mass. Total cholesterol and LDL-C were negatively related to maximal aerobic fitness (VO2max) (r=−0.37 and r=−0.33, respectively; P<0.05), while low-density-lipoprotein (LDL) size was positively related to VO2max (r=0.35, P<0.05).CONCLUSIONS: These results suggest that age-associated changes in lipoprotein concentrations are probably, in part, due to primary aging, rather than age-related changes in abdominal obesity and aerobic fitness.