Effects of intermittent fasting on cardiometabolic risk factors in patients with metabolic syndrome: A systematic review and meta-analysis of randomized controlled trials.

BACKGROUND AND OBJECTIVES: Evidence showed that intermittent fasting may have beneficial effects on metabolic syndrome. However, the results are controversial and indefinite. This study intends to investigate and assess the effects of intermittent fasting (IF) on cardiometabolic risk factors in patients with metabolic syndrome. METHODS AND STUDY DESIGN: We searched PubMed, Web of Science, Embase, and Cochrane Library databases up to July 31, 2022. Primary outcomes included body mass index, fat mass, fat free mass, body weight, blood pressure, the homeostasis model assessment of insulin resistance (IR), fasting blood glucose, fasting insulin, and lipid profiles. RESULTS: Of 4997 retrieved records, 6 met the inclusion criteria. The meta-analysis showed that IF can significantly reduce BMI (mean difference=-1.56 kg/m2, 95% CI: -2.62 to -0.51), fat mass (mean difference=-1.35%, 95% CI: -2.03 to -0.67), fat free mass (mean difference=-0.63%, 95% CI: -1.22 to -0.04), body weight (mean difference=-2.49 kg, 95% CI: -3.11 to -1.88), waist circumference (mean difference=-3.06 cm, 95% CI: -4.21 to -1.92), and HOMA-IR (mean difference=-0.62, 95% CI: -0.84 to -0.40) compared with non-fasting. However, no statistical difference was found in the SBP, DBP, TC, TG, LDL-C, HDL-C, fasting blood glucose, and fasting insulin comparing fasting and non-fasting group. Subgroup analyses suggested that study duration and sample size may be the source of heterogeneity for LDL-C. Sensitivity analysis indicated that our results are reliable and robust. CONCLUSIONS: IF could be used for patients with metabolic syndrome. Further studies with a larger sample size are needed to verify the effectiveness and safety of IF in patients with metabolic syndrome.