Effect of Epidemic Intermittent Fasting on Metabolic Syndrome: A Systematic Review and Meta-analysis of Randomized Controlled Trials

Abstract Background and aims: Intermittent fasting (IF) has gained attention as a promising diet for weight loss and dysmetabolic diseases management. This systematic review aimed to investigate the effects of IF on metabolic syndrome (MetS). Methods: A systematic literature search was carried out using three electronic databases, namely PubMed, Embase, and the Cochrane Library, until October 2020. Randomized controlled trials that compared the IF intervention with a control group diet were included. Effect sizes were expressed as weighted mean difference (WMD) using a fixed-effects model and 95% confidence intervals (CI). Results: Forty-six studies were included. Compared to the ones within control groups, participants exposed to the IF intervention reduced their body weight (WMD, -1.78 kg; 95% CI, -2.21 to -1.35; p < 0.05), waist circumference (WMD, -1.19 cm; 95% CI, -1.8 to -0.57; p < 0.05), fat mass (WMD, -1.26 kg; 95% CI, -1.57 to -0.95; p < 0.05), body mass index (WMD, -0.58 kg/m2; 95% CI, -0.8 to -0.37; p < 0.05), systolic blood pressure (WMD, -2.14 mmHg; 95% CI: -3.54 to -0.73; p < 0.05), diastolic blood pressure (WMD: -1.38 mmHg, 95% CI, -2.35 to -0.41, p < 0.05), fasting blood glucose (WMD, -0.96 mg/dL; 95% CI, -1.89 to -0.03; p < 0.05), fasting insulin (WMD, -0.8 μU/mL; 95% CI, -1.15 to -0.44; p < 0.05), insulin resistance (WMD, -0.21; 95% CI, -0.36 to -0.05; p < 0.05), total cholesterol (WMD, -3.75 mg/dL; 95% CI, -6.64 to -0.85; p < 0.05), triglycerides (WMD, -7.54 mg/dL; 95% CI, -11.45 to -3.63; p < 0.05). No effects were observed for low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, or glycosylated hemoglobin. Conclusions: This meta-analysis supports IF’s role in the improvement of MetS, compared to a control group diet. Further research on IF interventions should take into account long-term and well-designed administration to draw definitive conclusions.