Background: A chronic inflammatory state characterizes a wide range of diseases for which obesity is a risk factor. Weight loss could reduce levels of circulating inflammatory markers potentially reducing the incidence of associated diseases and improving response to treatment. However, dietary weight loss studies have reported inconsistent effects on serum inflammatory makers and the long-term effects are unknown.
Objective: To systematically review randomized controlled trials and analyze any differences in serum interleukin-6 and tumor necrosis factor-alpha between adults with obesity achieving weight loss through dietary intervention compared to those receiving none or standard care.
Methods: Studies were identified by searching databases from 1966 to November 2024. Randomized controlled trials with at least 12 months' follow-up were included in this systematic review and meta-analysis with an assessment of Cochrane risk of bias version 1.
Results: Twelve eligible studies were included. No trials reported a significant effect of weight loss on circulating tumor necrosis factor-alpha, whilst studies achieving greater than 5% weight loss significantly reduced circulating interleukin-6 in adults with obesity.
Conclusion: Weight loss interventions achieving and maintaining greater than 5% weight loss appear to be required to reduce circulating interleukin-6 levels in adults with obesity.
Keywords: diet; inflammation; inflammatory markers; multimorbidity; obesity; weight loss.
© 2025 The Author(s). Obesity Reviews published by John Wiley & Sons Ltd on behalf of World Obesity Federation.