Effects of Exercise and Caloric Restriction on Insulin Resistance and Cardiometabolic Risk Factors in Older Obese Adults--A Randomized Clinical Trial

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Abstract
The prevalence of insulin resistance, metabolic syndrome, and cardiovascular disease is greatest in older obese patients, and effective evidence-based treatment strategies are lacking. A prospective controlled study was conducted on 24 older (65.5 ± 5.0 years) obese (body mass index, 34.3 ± 5.2 kg/m2) adults with clinically diagnosed metabolic syndrome. We examined the effect of exercise alone (EX) or exercise combined with moderate caloric restriction (−500 kcal, EX + CR) on metabolic and cardiovascular risk factors. Measures of insulin sensitivity assessed by euglycemic hyperinsulinemic clamp and by oral glucose tolerance test, lipid profiles, blood pressure, body composition, abdominal fat, and aerobic capacity were all obtained before and after the interventions. Both groups experienced significant weight loss, but the reduction was greater in the EX + CR group than in the EX group (−6.8 ± 2.7 kg vs −3.7 ± 3.4 kg, respectively, p = .02). Both interventions improved insulin sensitivity (2.4 ± 2.4 mg/kg FFM/min and 1.4 ± 1.7 mg/kgFFM/min, respectively, p < .001) and indices of metabolic syndrome (systolic/diastolic blood pressure, waist circumference, glucose, and triglycerides; p < .05). High-density lipoprotein levels remained unchanged. Total abdominal, subcutaneous, and visceral fat; aerobic capacity; and total and low-density lipoprotein cholesterol were also improved. With the exception of weight loss and subcutaneous fat, there was no difference in the magnitude of improvement between the interventions. These data suggest that exercise alone is an effective nonpharmacological treatment strategy for insulin resistance, metabolic syndrome, and cardiovascular disease risk factors in older obese adults.