Diets
intermittent fasting decreases inflammatory markers CRP and IL-6
In plain terms: Does intermittent fasting lower inflammation markers like CRP and IL-6?
Part of: 🥗 intermittent fasting
Partly — pooled trials show a small but real drop in CRP, while IL-6 and TNF-alpha changes are inconsistent and much of the effect tracks weight loss rather than fasting per se.
📅 Last reviewed: 2026-07-15 ⓘ
Evidence ladder
How far up the ladder this claim has climbed. A high consensus on a low rung means "consistent so far," not "proven in people."
Top evidence so far: All trials, pooled (Meta-analysis)
How the studies fall
What the evidence shows
Pooled trials show a small real drop in interleukin-6, at a standardised mean difference of -0.30 across ten randomised trials. CRP is the weaker half: a six-month trial with circulating CRP as its pre-specified primary outcome found no significant reduction, and TNF-alpha changes are inconsistent, so the marker picture is partial rather than uniform.
The evidence (12)
| Source | Grade | Stance | Quality | Finding |
|---|---|---|---|---|
| Song Q, Almutairi ASH, Almutairi MFA, Jamilian P, Abu-Zaid A 2025 · Frontiers in nutrition | meta-analysis | mixed | moderate | IL-6 SMD=-0.30 (95% CI -0.57,-0.03), p=0.029, 10 RCTs/701 pts, GRADE-high; CRP not pooled |
| Jiao M, Yan H, Zhang B, Zhao X, Li J, Harun MT 2026 · Frontiers in nutrition | meta-analysis | mixed | low | 65 RCTs/3293 pts; EX+IF vs control significantly reduced IL-6 (direction reported, no pooled effect size in abstract) |
| Khalafi M, Habibi Maleki A, Mojtahedi S, Ehsanifar M, Rosenkranz SK, Symonds ME, Tarashi MS, Fatolahi S, Fernandez ML 2025 · Nutrients | meta-analysis | mixed | moderate | Systematic review and network meta-analysis reported IF modestly lowered some inflammatory markers, with heterogeneity across protocols and markers limiting confidence. |
| Faris M, Abdelrahim DN, El Herrag SE, Khaled MB, Shihab KA, AlKurd R, Madkour M 2025 · Clin Nutr ESPEN | meta-analysis | mixed | moderate | Off-scope: umbrella of 'Twenty meta-analyses' whose outcomes were BFP, fat mass, BMI, BW, WC, SBP, DBP, lipids, FBG, HbA1c, HOMA-IR, insulin, leptin and adiponectin — no CRP or IL-6. 'Results of continuous outcomes were pooled from included meta-analyses' (would be review anyway). |
| Barve RA, Veronese N, Bertozzi B, Tosti V, Cagigas ML, Spelta F, Cava E, Piccio L, Early DS, Head RD, Fontana L 2025 · Nat Commun | RCT | contradicts | moderate | 6-month IF RCT whose pre-specified primary outcome (circulating CRP) showed no significant reduction versus habitual diet despite 8% weight loss. |
| Allocca S, Monda A, Casillo M, Moscatelli F, La Marra M, Monda V, Maio GD, Cincione RI, Vasco P, Monda M, Polito R, Messina G, Messina A 2026 · Medicina (Kaunas, Lithuania) | observational | supports | low | 3-arm 12mo trial (16:8, 5:2, MedDiet), n=30; abstract reports 'more rapid improvement' in CRP/TNF-a/IL-6/IL-10 vs MedDiet, no Δ/CI/p given |
| Aamir AB, Kumari R, Latif R, Ahmad S, Rafique N, Salem AM, Alasoom LI, Alsunni A, Alabdulhadi AS, Chander S 2025 · Obes Rev | meta-analysis | tested-null | moderate | Meta-analysis of RCTs (>=8 wk) in obesity/overweight vs unrestricted or ad libitum feeding, fixed-effect SMDs; abstract only (not open access). For intermittent fasting (6 RCTs): 'No associations were detected between IF and CRP or IL-6' - a null on both of the claim's markers; the IF point estimates are not in the abstract, so clean null vs underpowered trend is cannot-tell from available text. The CRP (SMD -0.15, -0.30 to -0.00) and IL-6 (SMD -0.31, -0.51 to -0.10) reductions belong to continuous caloric restriction (15 RCTs), not IF; IF lowered TNF-alpha (SMD -0.32, -0.63 to -0.02), which is off the claim's object. Authors: 'CR may be more effective in reducing chronic low-grade inflammation than IF'; some concerns on randomization/allocation concealment. |
| Turner L, Zhao L, Liu K, Teong XT, Wittert G, Hutchison AT, Heilbronn LK 2025 · J Hum Nutr Diet | RCT | contradicts | low | Exploratory sub-study of a 6-mo RCT (N=209, adults at T2D risk): iTRE (30% energy needs 0800-1200 on 3 d/wk) vs 30% CR vs standard care. Markers measured 'in a subset with weight loss above (CR: N = 32, iTRE: N = 35) or below median (SC: N = 18)'. CRP fell over time overall (-1.36 +/- 0.47 mg/dL, p < 0.001) but 'there were no between group effects', including iTRE vs SC; no adipose-tissue gene differences. Null despite a weight-loss-enriched iTRE subset; subset selection breaks randomisation. |
| Ranjbar M, Shab-Bidar S, Rostamian A, Mohammadi H, Tavakoli A, Djafarian K 2025 · Complement Ther Med | RCT | contradicts | moderate | RCT, 44 overweight/obese postmenopausal women with rheumatoid arthritis, 16/8 IF vs usual diet for 8 weeks; hs-CRP, ESR and IL-6 were secondary outcomes. 'The IF diet significantly improved BMI, DAS-28, CDAI, and HAQ (p-value<0.05 for all). However, there were no significant effects on the other study outcomes.' Authors: IF 'has no significant impact on inflammation and oxidative stress markers.' Null on CRP/IL-6; no effect sizes in the abstract. |
| Wang X, Yang Q, Liao Q, Li M, Zhang P, Santos HO, Kord-Varkaneh H, Abshirini M 2020 · Nutrition | meta-analysis | supports | moderate | Meta-analysis of 18 RCTs found IF and energy-restricted diets significantly reduced CRP (WMD -0.024 mg/dL), with no consistent effect on other cytokines, in overweight/obese adults. |
| Jahrami H, Ammar A, Glenn JM, Saif Z, Chtourou H, Trabelsi K 2025 · Nutr Rev | meta-analysis | mixed | moderate | Umbrella meta-analysis of syntheses: 'Eleven systematic reviews and meta-analyses were included in the current umbrella review.' Outcomes were nine metabolic-syndrome components (waist, weight, lipids, BP, fasting glucose); no CRP or inflammatory marker was analysed, so the earlier 'inconsistent inflammatory-marker effects' is not in the abstract. Review — zero weight (also off-outcome). |
| Zouhal H, Bagheri R, Ashtary-Larky D, Wong A, Triki R, Hackney AC, Laher I, Abderrahman AB 2020 · Physiol Behav | observational | supports | low | Ramadan intermittent fasting in men with obesity lowered CRP, IL-6 and TNF-alpha over the fasting month. |
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