Effects of weight loss on insulin sensitivity and arterial stiffness in overweight adults.
ABSTRACT Obesity is characterized by metabolic and vascular abnormalities. We examined the effects of weight loss on insulin sensitivity and arterial stiffness in overweight adults. Twelve (9 females; 3 males) overweight (body mass index, 30.3 +/- 3.7) adults (54.9 +/- 3.9 years) without diabetes or vascular disease were counseled by a registered dietician to lose weight over 6 months. Vascular structure, function, and wall mechanical properties were measured via ultrasound. Intravenous glucose tolerance test, 24-hour blood pressure, body composition (dual-energy x-ray absorptiometry), and lipids were also assessed. There were significant reductions in body mass (86.3 +/- 14.2 vs 79.5 +/- 13.8 kg, P < .0001) and percentage of fat (44.3% +/- 7.0% vs 41.0% +/- 8.5%, P < .01) after weight loss. There were significant improvements in total cholesterol (6.0 +/- 0.9 vs 5.0 +/- 0.8 mmol/L, P < .0001), low-density lipoprotein cholesterol (3.9 +/- 0.7 vs 3.2 +/- 0.6 mmol/L, P < .0001), triglycerides (3.4 +/- 2.3 vs 2.4 +/- 0.9 mmol/L, P < .05), and insulin sensitivity (3.3 +/- 1.7 vs 5.4 +/- 1.6 microU x 10(-4) min(-1) mL(-1), P < .0001) after weight loss. Brachial artery compliance (P < .05) and distensibility (P < .05) curves over the physiologic pressure range improved, whereas endothelial function and intima-media thickness remained unchanged. In overweight adults, 6 months of weight loss resulted in improvements in body composition, insulin sensitivity, lipid profile, and brachial artery compliance and distensibility.
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ABSTRACT: Impaired vascular endothelial function may be an important mechanism linking obesity to increased cardiovascular risk. We investigated whether short-term weight loss improves conduit artery endothelial dysfunction in overweight adults. Forty-three otherwise healthy overweight patients with a body mass index > or =27 kg/m(2) completed an open-label 3-month trial consisting of a calorie-restricted diet and 120 mg of orlistat taken 3 times daily with meals. Endothelial function and parameters of the metabolic syndrome were measured before and after intervention. Subjects lost 6.6 +/- 3.4% of their body weight. Low-density lipoprotein cholesterol, low-density lipoprotein concentration, fasting insulin, and leptin decreased significantly (all p <0.009), and C-reactive protein decreased (p = 0.22). Conduit vascular function did not change as assessed by flow-mediated dilation (3.86 +/- 3.54 vs 3.74 +/- 3.78%, p = 0.86) and nitroglycerin-mediated dilation (17.18 +/- 5.89 vs 18.87 +/- 7.11%, p = 0.13) of the brachial artery. A moderate degree of weight reduction over 3 months improved the metabolic syndrome profile but not the vascular dysfunction associated with uncomplicated obesity.The American Journal of Cardiology 04/2004; 93(8):1012-6. · 3.21 Impact Factor
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ABSTRACT: The effects of smooth muscle relaxation on arterial wall mechanics are controversial. We used a new, in vivo, noninvasive technique to measure brachial artery wall mechanics under baseline conditions and following smooth muscle relaxation with nitroglycerin (NTG). Eight healthy, normal subjects (6 male, 2 female; age 30+/-3.1 years) participated in the study. The nondominant brachial artery was imaged through a water-filled blood pressure cuff using an external ultrasound wall-tracking system at baseline and following 0.4 mg sublingual NTG. Simultaneous radial artery pressure waveforms were recorded by tonometry. Transmural pressure (TP) was reduced by increasing water pressure in the cuff. Brachial artery area, unstressed area, compliance, stress, strain, incremental elastic modulus (Einc), and pulse wave velocity (PWV) were measured over a TP range from 0 to 100 mm Hg. Baseline area versus TP curves generated 30 minutes apart were not significantly different. NTG significantly shifted area versus TP (P<0.0001) and compliance versus TP (P<0.001) curves upward, whereas the Einc versus TP (P<0.05) and PWV versus TP (P<0. 01) curves were shifted downward. NTG also significantly shifted stress versus strain (P<0.01) and Einc versus strain (P<0.01) curves to the right. We conclude that brachial artery elastic mechanics can be reproducibly measured over a wide range of TP and smooth muscle tone using a new noninvasive ultrasound technique. Smooth muscle relaxation with NTG increases isobaric compliance and decreases isobaric Einc and PWV in the human brachial artery.Circulation 07/1999; 100(1):41-7. · 15.20 Impact Factor
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ABSTRACT: The number of days of food intake data needed to estimate the intake of 29 male (n = 13) and female (n = 16) adult subjects, individually and as a group, was determined for food energy and 18 nutrients. The food intake records were collected in a year-long study conducted by the U.S. Department of Agriculture's Beltsville Human Nutrition Research Center. Each individual's average intake of nutrients and standard deviation over the year were assumed to reflect his or her "usual" intake and day-to-day variability. Confidence intervals (P less than 0.05) for each individual's usual intake were constructed, and from these the number of days of dietary records needed for estimated individual and group intake to be within 10% of usual intake was calculated. The results indicated that the number of days of food intake records needed to predict the usual nutrient intake of an individual varied substantially among individuals for the same nutrient and within individuals for different nutrients; e.g., food energy required the fewest days (averaging 31) and vitamin A the most (averaging 433). This was considerably higher than the number of days needed to estimate mean nutrient intake for this group, which ranged from 3 for food energy to 41 for vitamin A. Fewer days would be needed for larger groups.Journal of Nutrition 10/1987; 117(9):1638-41. · 4.20 Impact Factor