Effect of Intermittent Fasting on Liver Function Tests: A Systematic Review and Meta-Analysis of Randomized Clinical Trials

Abstract Context Intermittent fasting (IF) is a diet strategy with alternate intervals of calorie reduction and normal eating. Despite its beneficial effects on weight loss and cardiometabolic risk factors, the effect of IF on liver function tests (LFTs) remains unclear. Objective This study aimed to investigate the effect of IF on LFTs through a systematic review and meta-analysis of randomized clinical trials. Data Sources An electronic search was performed using predefined search terms in databases including PubMed, Scopus, and ISI Web of Science until February 2023. Data Extraction The studies were selected according to PRISMA guidelines, and the risk of bias was assessed for the randomized controlled trials. Data Analysis The results of this study are reported as weighted mean differences (WMDs) with 95% CIs. Fourteen RCTs were included in the meta-analysis, with a total sample size of 908. IF significantly reduced alanine aminotransferase (ALT) (WMD: −2.88, 95% CI: −4.72 to −1.04, P-value = .002) and aspartate aminotransferase (AST) levels (WMD: −1.67, 95% CI: −3.12 to −0.22, P-value = .024). The results of the subgroup analysis showed that the impact of IF was significant in both the nonalcoholic fatty liver disease and the healthy groups for ALT. The effects of IF on the serum gamma-glutamyl transpeptidase (GGT) level were significant (WMD: −3.19, 95% CI: −6.00 to −0.39, P-value = .026), but there were no significant changes in the alkaline phosphatase (ALP) level (WMD: 1.06, 95% CI: −0.23 to 2.34, P-value = .106). Furthermore, no substantial heterogeneity between studies was reported. Conclusion IF can improve ALT, AST, and GGT levels but not ALP enzyme levels and may have a benefit on liver function. Systematic Review Registration PROSPERO registration no. CRD42023396211.