Additional effects of exercise to hypocaloric diet on body weight, body composition, glycaemic control and cardio-respiratory fitness in adults with overweight or obesity and type 2 diabetes

Aims: This systematic review and meta-analysis evaluates the additional effect of exercise to hypocaloric diet on body weight, body composition, glycaemic control and cardio-respiratory fitness in adults with overweight or obesity and type 2 diabetes. Methods: Embase, Medline, Web of Science and Cochrane Central databases were evaluated, and 11 studies were included. Random-effects meta-analysis was performed on body weight and measures of body composition and glycaemic control, to compare the effect of hypocaloric diet plus exercise with hypocaloric diet alone. Results: Exercise interventions consisted of walking or jogging, cycle ergometer training, football training or resistance training and duration varied from 2 to 52 weeks. Body weight and measures of body composition and glycaemic control decreased during both the combined intervention and hypocaloric diet alone. Mean difference in change of body weight (−0.77 kg [95% CI: −2.03; 0.50]), BMI (−0.34 kg/m² [95% CI: −0.73; 0.05]), waist circumference (−1.42 cm [95% CI: −3.84; 1.00]), fat-free mass (−0.18 kg [95% CI: −0.52; 0.17]), fat mass (−1.61 kg [95% CI: −4.42; 1.19]), fasting glucose (+0.14 mmol/L [95% CI: −0.02; 0.30]), HbA_1c (−1 mmol/mol [95% CI: −3; 1], −0.1% [95% CI: −0.2; 0.1]) and HOMA-IR (+0.01 [95% CI: −0.40; 0.42]) was not statistically different between the combined intervention and hypocaloric diet alone. Two studies reported VO_2max and showed significant increases upon the addition of exercise to hypocaloric diet. Conclusions: Based on limited data, we did not find additional effects of exercise to hypocaloric diet in adults with overweight or obesity and type 2 diabetes on body weight, body composition or glycaemic control, while cardio-respiratory fitness improved.