Weight loss, exercise or both and cardiometabolic risk factors in obese older adults: results of a randomized controlled trial

BACKGROUND: Obesity exacerbates the age-related decline in insulin sensitivity and is associated with risk for cardiometabolic syndrome in older adults; however, the appropriate treatment for obese older adults is controversial. OBJECTIVE: To determine the independent and combined effects of weight loss and exercise on cardiometabolic risk factors in obese older adults. DESIGN: One-hundred and seven obese (body mass index (BMI) >= 30 kg m(-2)) older (>= 65 years) adults with physical frailty were randomized to control group, diet group, exercise group and diet-exercise group for 1 year. Outcomes for this study included changes in insulin sensitivity index (ISI), glucose tolerance, central obesity, adipocytokines and cardiometabolic syndrome. RESULTS: Although similar increases in ISI occurred in the diet-exercise and diet groups at 6 months, the ISI improved more in the diet-exercise than in the diet group at 12 months (2.4 vs 1.2; between-group difference, 1.2; 95% confidence interval, 0.2-2.1); no changes in ISI occurred in both exercise and control groups. The diet-exercise and diet groups had similar improvements in insulin area under the curve (AUC) (-2.9 and -2.9 x 10(3) mg min dl(-1)), glucose AUC (-1.4 and -2.2 x 10(3)mg min dl(-1)), visceral fat (-787 and -561 cm(3)), tumor necrosis factor (-17.0 and -12.8 pg ml(-1)), adiponectin (5.0 and 4.0 ng ml(-1)), waist circumference (-8.2 and -8.4 cm), triglyceride (-30.7 and -24.3 g dl(-1)) and systolic/diastolic blood pressure (-15.9 and -13.1/-4.9 and 6.7 mm Hg), while no changes in these parameters occurred in both exercise and control groups. The cardiometabolic syndrome prevalence decreased by 40% in the diet-exercise and by 15% in the diet group. Body weight decreased similarly in the diet-exercise and diet groups (-8.6 and -9.7 kg) but not in the exercise and control groups. CONCLUSIONS: In frail, obese older adults, lifestyle interventions associated with weight loss improve insulin sensitivity and other cardiometabolic risk factors, but continued improvement in insulin sensitivity is only achieved when exercise training is added to weight loss.