Exercise training and dietary glycemic load may have synergistic effects on insulin resistance in older obese adults

Abstract

Background/aims: The aim of this study was to assess the combined effects of exercise and dietary glycemic load on insulin resistance in older obese adults.

Methods: Eleven men and women (62 +/- 2 years; 97.6 +/- 4.8 kg; body mass index 33.2 +/- 2.0) participated in a 12-week supervised exercise program, 5 days/week, for about 1 h/day, at 80-85% of maximum heart rate. Dietary glycemic load was calculated from dietary intake records. Insulin resistance was determined using the euglycemic (5.0 mM) hyperinsulinemic (40 mU/m(2)/min) clamp.

Results: The intervention improved insulin sensitivity (2.37 +/- 0.37 to 3.28 +/- 0.52 mg/kg/min, p < 0.004), increased VO(2max) (p < 0.009), and decreased body weight (p < 0.009). Despite similar caloric intakes (1,816 +/- 128 vs. 1,610 +/- 100 kcal/day), dietary glycemic load trended towards a decrease during the study (140 +/- 10 g before, vs. 115 +/- 8 g during, p < 0.04). The change in insulin sensitivity correlated with the change in glycemic load (r = 0.84, p < 0.009). Four subjects reduced their glycemic load by 61 +/- 8%, and had significantly greater increases in insulin sensitivity (78 +/- 11 vs. 23 +/- 8%, p < 0.003), and decreases in body weight (p < 0.004) and plasma triglycerides (p < 0.04) compared to the rest of the group.

Conclusion: The data suggest that combining a low-glycemic diet with exercise may provide an alternative and more effective treatment for insulin resistance in older obese adults.