Effects of intermittent fasting and caloric restriction on inflammatory biomarkers in individuals with obesity/overweight: A systematic review and meta‐analysis of randomized controlled trials

Summary Introduction Obesity is characterized by chronic low‐grade inflammation. This study presents an updated systematic review and meta‐analysis on the effect of caloric restriction (CR) and intermittent fasting (IF) on plasma inflammatory biomarkers (C‐reactive protein [CRP], tumor necrosis factor [TNF]‐alpha, and interleukin [IL]‐6) in individuals with obesity/overweight compared with unrestricted or ad libitum feeding. Methods PubMed, Web of Science, and SCOPUS databases were searched for randomized controlled trials (RCTs) reporting inflammatory biomarkers after at least 8 weeks of intervention. Standardized mean differences (SMDs) were calculated using a fixed effect model. Heterogeneity was determined using I 2 statistics. Sensitivity analysis was conducted using the “leave‐one‐out” approach. Results Relatively few RCTs have investigated the effect of IF on inflammatory biomarkers than with CR (6 vs. 15). Analysis of pooled data showed that CR was associated with a significant reduction in CRP with low heterogeneity (SMD −0.15 mg/L [95% CI −0.30 to −0.00], p = 0.04; I 2 = 0%, p = 0.69) and IL‐6 with high heterogeneity (SMD −0.31 pg/mL [95% CI −0.51 to −0.10], p = 0.004; I 2 = 73%, p = 0.001). IF was associated with a significant decrease in TNF‐alpha with moderate heterogeneity (SMD −0.32 pg/mL [95% CI −0.63 to −0.02], p = 0.04; I 2 = 44%, p = 0.13). No associations were detected between IF and CRP or IL‐6 and CR and TNF‐alpha. Conclusion CR may be more effective in reducing chronic low‐grade inflammation than IF. However, there were some concerns regarding the included studies' randomization and allocation sequence concealment process.