The antioxidative effects of exercise training-and diet-induced weight loss
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[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] Obesity and insulin resistance (IR) increase the risk for coronary heart disease (CHD); however, much of this risk is not attributable to traditional risk factors. Elevated oxidative stress associated with obesity may represent a link between IR and CHD. PURPOSE: The purpose of the current investigation was to determine whether weight loss beneficially alters biomarkers of oxidative stress and whether these alterations are associated with improvements in measures of insulin resistance. METHODS: Twentyfive sedentary and overweight to obese [body mass index (BMI) = 33.0 [plus-minus sign] 0.8 kg/m[superscript 2] ] individuals (8 males, and 17 females, age = 40 [plus-minus sign] 2 y), with characteristics of the metabolic syndrome, participated in a 4-7 months weight loss program that consisted of both energy restriction ([approximate sign]600 kcal/d) and supervised aerobic exercise (5 d/wk, 45 min/d at 60% VO[subscript 2]max; [approximate sign]375 kcal/d). Fasting blood samples were collected at baseline and post weight loss for the determination of insulin and glucose. IR and insulin sensitivity were assessed by the calculation of the homeostasis model assessment (HOMA) and quantitative insulin sensitivity check index (QUICKI), respectively. Oxidative stress was assessed by oxidized LDL (oxLDL), myeloperoxidase (MPO), and low- and highdensity lipoprotein (LDL and HDL) lipid hydroperoxide levels in serum. Antioxidative status was determined by apolipoprotein A1 (apoA1) concentrations and paraoxonase-1 (PON1) activity and protein concentrations. RESULTS: Aerobic training- and dietinduced weight loss (9.3 [plus-minus sign] 0.3%; mean [plus-minus sign] SE) significantly (p [less-than sign] 0.05) increased insulin sensitivity and reduced insulin resistance, oxLDL, and LDL lipid hydroperoxides, but did not alter HDL lipid hydroperoxides or MPO levels. The lifestyle intervention impacted systemic antioxidative status by increasing apoA1 concentrations and reducing serum PON1 protein and activity levels. Changes in oxidative stress were not associated with alterations in HOMA or QUICKI. CONCLUSION: Diet- and exercise-induced weight loss ([approximate sign]10%) beneficially alters biomarkers of oxidative status and increases measures of insulin sensitivity. Lifestyle modifications represent a means by which to reduce disease risk associated with obesity.
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