Short-Term Moderate Weight Loss and Resistance Training Do Not Affect Insulin-Stimulated Glucose Disposal in Postmenopausal Women

Abstract

OBJECTIVES—Moderate weight loss and exercise have been proposed as important tools in the treatment and prevention of type 2 diabetes. Therefore, we tested the hypothesis that short-term (4 weeks) moderate energy restriction (−750 kcal/day) would result in a significant increase in insulin-stimulated glucose disposal (40 mU · m⁻² · min⁻¹ hyperinsulinemic-euglycemic clamp) in moderately overweight postmenopausal women and that when combined with resistance training (RT) an even greater effect would be seen.

RESEARCH DESIGN AND METHODS—Older women were randomly assigned to energy restriction (WLoss group; n = 9) or energy restriction plus RT (RT + WLoss group; n = 10).

RESULTS—For the WLoss versus the RT + WLoss groups, changes in body weight (−3.0 ± 0.2 kg vs. −3.2 ± 0.3 kg), fat mass (FM) (−3.0 ± 0.3 kg vs. −3.2 ± 0.3 kg), and percent body fat (BF) (−2.1 ± 0.4 vs. −2.4 ± 0.3%) were not different between groups. Muscle mass (group-by-time interaction, P = 0.04) was preserved in RT + WLoss (0.40 ± 0.40 kg) and reduced in WLoss (−0.64 ± 0.18 kg). There were no changes in fat-free mass (FFM) and waist-to-hip ratio in either group. Whole body glucose disposal (WLoss 6.14 ± 0.57 vs. 6.03 ± 0.53, RT + WLoss 5.85 ± 0.60 vs. 6.09 ± 0.56 mg/kg of FFM/min) did not change in either group.

CONCLUSIONS—The results of this study demonstrate that short-term energy restriction resulting in moderate decreases in body weight (4.0 ± 0.3%) and FM (8.2 ± 0.7%) did not improve insulin-stimulated glucose disposal. The addition of RT to the hypoenergetic diet preserved muscle mass but provided no synergistic effect on insulin action. These results suggest that a greater change in body weight or FM may be necessary to observe a significant improvement in insulin action.