Effects of caloric restriction with different doses of exercise on fat loss in people living with type 2 diabetes: A secondary analysis of the DOSE-EX randomized clinical trial

BACKGROUND: Fat loss mainly conveys the benefits of caloric restriction for people living with type 2 diabetes. The literature is equivocal regarding whether exercise facilitates fat loss during caloric restriction. This analysis aimed to assess the dose-response effects of exercise in combination with a caloric restriction on fat mass (FM) and FM percentage (FM%) in persons with diagnosed type 2 diabetes.

METHODS: In this secondary analysis of a 4-armed randomized trial, 82 persons living with type 2 diabetes were randomly allocated to the control group (CON) (n = 21), diet control (DCON) (25% caloric restriction; n = 20), diet control and exercise 3 times per week (MED) (n = 20), or diet control and exercise 6 times per week (HED) (n = 21) for 16 weeks. The primary analysis was the change in FM% points. Secondary analyses included fat-free mass and visceral adipose tissue (VAT) volume (cm 3).

RESULTS: FM% decreased compared to CON by a mean difference of -3.5% (95% confidence interval (95%CI): -5.6% to -1.4%), -6.3% (95%CI: -8.4% to -4.1%), and -8.0% (95%CI: -10.2% to -5.8%) for DCON, MED, and HED, respectively. Compared to DCON, MED, and HED decreased FM% by -2.8% (95%CI: -4.9% to -0.7%) and -4.5% (95%CI: -6.6% to -2.4%), respectively. The difference in FM% between HED and MED was -1.8% (95%CI: -3.9% to 0.4%). DCON and MED decreased fat-free mass compared to CON, whereas HED preserved fat-free mass (-0.2%; 95%CI: -2.0% to 1.7%). Compared to CON, VAT volume decreased by -666.0 cm 3 (95%CI: -912.8 cm 3 to -385.1 cm 3), -1264.0 cm 3 (95%CI: -1679.6 cm 3 to -655.9 cm 3), and -1786.4 cm 3 (95%CI: -2264.6 cm 3 to -1321.2 cm 3) more for DCON, MED, and HED, respectively. HED decreased VAT volume more than DCON (-1120.4 cm 3; 95%CI: -1746.6 cm 3 to -639.4 cm 3) while the remaining comparisons did not reveal any differences.

CONCLUSION: All interventions were superior in reducing FM% compared to standard care. Adding exercise to a caloric restriction was superior in reducing FM% compared to a caloric restriction alone.