One-year caloric restriction and 12-week exercise training intervention in obese adults with type 2 diabetes: emphasis on metabolic control and resting metabolic rate

Purpose: The effect of combined lifestyle interventions (LSI) including dietary and physical activity on metabolic health, energy metabolism and VO2max in diabetic patients has provided mixed results. We evaluated the impact of 1-year caloric restriction (CR), and 12-week supervised structured exercise training (SSET) on metabolic health, RMR and VO2max in obese adults with type 2 diabetes. Methods: After 1-month education for LSI, 33 participants had anthropometric, biochemical and metabolic assessments. They then started CR based on RMR, and 3-month SSET during the months 1–3 (Early-SSET) or 4–6 (Late-SSET). Reassessments were planned after 3, 6 and 12 months. Using a per-protocol analysis, we evaluated parameter changes from baseline and their associations for the 23 participants (11 Early-SSET, 12 Late-SSET) who completed the study. RMR was adjusted (adjRMR) for age, sex, fat-free mass (FFM) and fat mass (FM). Results: Compared with baseline, after 6 months we found significant increases in VO2max (+ 14%) and HDL-cholesterol (+ 13%), and reduction in body mass index (− 3%), FM (− 8%) and glycated hemoglobin (HbA1c, − 7%). Training-related caloric expenditure negatively correlated with changes in body weight (p < 0.001), FM (p < 0.001) and HbA1c (p = 0.006). These results were confirmed at the 12-month follow-up. Pooling together all follow-up data, adjRMR changes correlated with changes in glycemia (r = 0.29, p = 0.02), total-cholesterol (r = 0.29, p = 0.02) and VO2max (r = − 0.26,p = 0.02). No significant differences emerged between the Early- and Late-SSET groups. Conclusions: Combined intervention with SSET and CR improved metabolic control. Changes in metabolic health and fitness correlated with changes of adjRMR, which was reduced improving fitness, glycemia and cholesterolemia. Clinical trial registry: Trial registration number: NCT03785379. URL of registration: http://clinicaltrials.gov.