Medicine & Science in Sports & Exercise:
G-26 Featured Science Session - Exercise, Obesity, and Metabolic Risk: SATURDAY, JUNE 2, 2007 9:00 AM - 11:00 AM ROOM: 354
Rector, R. Scott; Warner, Shana O.; Liu, Ying; Hinton, Pamela S.; Thomas, Tom R.
University of Missouri-Columbia, Columbia, MO.
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. Elevations in oxidative stress associated with obesity may represent a link between IR and CHD.
PURPOSE: We sought to determine whether weight loss beneficially alters biomarkers of oxidative stress and whether these alterations were associated with improvements in measures of insulin resistance.
METHODS: Twenty-five sedentary and overweight to class II obese [body mass index (BMI) = 33.0 ± 0.8 kg/m2] individuals (8 males, and 17 females, age = 40 ± 2 y), with characteristics of the metabolic syndrome, participated in a 4–7 m weight loss program that consisted of both energy restriction (∼600 kcal/d) and supervised aerobic exercise (5 d/wk, 45 min/d at 60% VO2max; ∼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 high- density lipoprotein (LDL and HDL) lipid hydroperoxide levels. Antioxidative status was determined by apolipoprotein A1 (apoA1) concentrations and paraoxonase-1 (PON1) activity and protein concentrations.
RESULTS: Aerobic training- and diet-induced weight loss (9.3 ± 0.3%; mean ± SE) significantly (p < 0.05) increased insulin sensitivity and reduced insulin resistance, oxLDL, and LDL lipid hydroperoxides, but did not alter HDL lipid hydroperoxides or MPO levels. However, 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 (∼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.
supported by NIH RO1 DK67036 and NIH T32 AR48523.