Effects of Intermittent-Fasting and Time-Restricted Eating Protocols on Cardiometabolic Outcomes in Adults with Metabolic Risk: A Meta-Analysis of Randomized Controlled Trials

Background: Intermittent-fasting interventions range from daily time-restricted eating to multiday modified fasting, and their cardiometabolic effects may differ by protocol and baseline metabolic status. Objective: To describe pooled effects on triglycerides, HDL cholesterol, systolic blood pressure, and fasting glucose among adults across metabolic-risk populations. Methods: The source review searched PubMed/MEDLINE, ScienceDirect, and Google Scholar and reported randomized clinical trials with heterogeneous fasting protocols. Pooled standardized mean differences (SMDs) and heterogeneity were transcribed from the supplementary forest plots. Results: Seven studies were listed, but their distinct populations included healthy volunteers without obesity, adults with obesity or diabetes, and individuals with metabolic syndrome. The reported effects were not statistically significant: triglycerides (five estimates, SMD -0.69, 95% CI -1.43 to 0.05; I² 82.17%), HDL cholesterol (five, -0.23, -0.76 to 0.30; I² 47.98%), systolic blood pressure (four, -0.44, -1.46 to 0.59; I² 81.58%), and fasting glucose (seven estimates, -0.65, -1.75 to 0.45; I² 94.96%). Two glucose estimates represent intervention arms sharing a control group. Conclusions: The available pooled estimates are imprecise and cannot establish cardiometabolic efficacy for any single fasting protocol or a population restricted to metabolic syndrome. Eligibility differences, high heterogeneity, and possible non-independence of comparisons warrant caution.