Intermittent fasting for rheumatic diseases: a systematic review and meta-analysis of conflicting evidence from observational studies and randomized controlled trials

Background and Objectives Intermittent fasting (IF) has emerged as a dietary approach with potential therapeutic effects that is gaining recognition. Although several studies have explored the impact of IF on clinical symptoms in patients with rheumatic diseases, a quantitative synthesis of the existing evidence is lacking. This study aims to systematically evaluate the overall effects of IF on disease activity and inflammatory markers in patients with rheumatic diseases. Methods A systematic search was conducted in PubMed, Web of Science, Embase, and The Cochrane Library for clinical studies examining intermittent fasting interventions in rheumatic diseases, with a search deadline of March 15, 2026. RevMan 5.4 software was utilized to perform a meta-analysis on the studies that met the inclusion criteria. Results A total of seven independent studies (yielding nine datasets) were included in the analysis, comprising 471 patients with rheumatoid arthritis (RA) and 85 patients with spondyloarthritis (SpA). The results indicated that observational studies, which provide a lower level of evidence, demonstrated significant improvements in disease activity scores associated with intermittent fasting ( e.g ., Visual Analog Scale (VAS), P < 0.05; Disease Activity Score in 28 joints (DAS28), P < 0.05). Additionally, an analysis of three randomized controlled trials (RCTs) revealed that (IF) significantly reduced DAS28 scores (MD = −0.55, 95% CI [−1.09 to −0.02], P = 0.04). Conclusion These findings suggest a positive effect of intermittent fasting on disease activity, as indicated by both observational studies and RCTs. However, the reliability of the conclusions drawn from RCTs is limited due to the small number of studies and considerable heterogeneity in the interventions. There is an urgent need for more rigorously designed RCTs to further validate these results.