The Effects of Intermittent Fasting on Inflammatory Markers in Adults: A Systematic Review and Pairwise and Network...

Background: Intermittent fasting (IF) can improve inflammatory status, but its effects may be dependent on the mode of fasting. Objectives: We performed a systematic review with pairwise and network meta-analyses to investigate the effects of different modes of IF on inflammatory markers in adults. Methods: Three database searches were conducted, including PubMed, Scopus, and Web of Science, from inception to June 2024. The searches used two keyword groups: "intermittent fasting" and "inflammatory markers". Randomized and non-randomized trials investigating any IF mode on inflammatory markers, including interleukin (IL)-6, tumor necrosis factor (TNF)α, C-reactive protein (CRP), leptin, and adiponectin, were included. Standardized mean differences (SMDs) were calculated using random effects models for both analyses. Results: A total of 21 studies (839 participants) were included. Compared with controls, IF reduced TNF-α [SMD: -0.31, p = 0.009], CRP [SMD: -0.19, p = 0.04], and leptin [SMD: -0.57, p = 0.005] but did not significantly affect IL-6 or adiponectin. Among the IF modes, time-restricted feeding (TRF) showed the largest reduction in TNF-α [-0.39, p = 0.001]. TRF had the highest probability ranking for changes in IL-6, TNF-α, leptin, and adiponectin; however, the effects on IL-6 and adiponectin were not statistically significant. The 5:2 diet ranked highest for CRP. Conclusions: IF may be an effective dietary therapy for improving some inflammatory markers, with effects potentially influenced by the mode of IF. TRF had the highest rankings across multiple markers, though the findings were not uniformly significant. Additional longer-term trials are needed to fully elucidate the anti-inflammatory potential of IF.