Intermittent fasting for weight management and metabolic health: An updated comprehensive umbrella review of health outcomes.

Aims: To provide an updated comprehensive evaluation of the quality and evidence association of existing studies on health outcomes related to intermittent fasting (IF).

Materials and methods: We conducted a systematic search of PubMed, Web of Science, Cochrane Library, and Embase databases, covering literature up to June 2024. Meta-analyses and systematic reviews that include adult populations and quantitatively analyse health outcomes related to IF interventional studies are included. For evidence with complete data, we reanalyzed health evidence effect sizes and 95% confidence intervals using random-effects models. Article quality and the certainty of the evidence were graded using A Measurement Tool to Assess Systematic Reviews (AMSTAR-2), Grading of Recommendations Assessment, Development and Evaluation (GRADE) system, and a standardized credibility grading system.

Results: Twelve meta-analysis studies and 122 health outcome associations with IF were identified. High-quality evidence indicated significant associations between time-restricted eating (TRE) and weight loss, fat mass reduction, decreased fasting insulin and glycosylated haemoglobin levels in overweight or obese adults, as well as between the 5:2 diet and reduced low-density lipoprotein cholesterol levels. Moderate-to-low-quality evidence suggested associations between modified alternate-day fasting and improvements in body weight, lipid profile and blood pressure. Additionally, high-to-low-quality evidence showed that IF regimens effectively improved liver health in non-alcoholic fatty liver disease.

Conclusions: This umbrella review highlights IF, especially TRE, as a promising intervention for weight and metabolic health, particularly beneficial for overweight or obese adults. We also highlight the need for further extensive research to understand the long-term effects, individualized IF plans and potential adverse effects of IF in different populations.