Abstract
OBJECTIVES: The 2019 Lancet Commission report introduced the concept of a 'syndemic', emphasising the complex interplay between malnutrition, obesity and climate change. This updated systematic review aimed to synthesise evidence after 2019 on climate change and childhood obesity. DESIGN: Systematic literature review using Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. DATA SOURCES: Four English databases (MEDLINE, Embase, Scopus and CINAHL) and four Chinese databases (China National Knowledge Infrastructure (CNKI), Wanfang, CQVIP and SinoMed), covering publications from 1 January 2019 to 20 August 2024. ELIGIBILITY CRITERIA FOR SELECTING STUDIES: We included studies examining the impact of climate-related and weather-related exposures on obesity-related outcomes among children aged 2-12 years; quantitative and qualitative studies exploring their interrelationships. DATA EXTRACTION AND SYNTHESIS: Two independent reviewers used standardised methods to search, screen and code included studies. Risk of bias (RoB) was assessed using the RoB Rating Tool for Human and Animal Studies. Findings were summarised and synthesised with key characteristics, including sociodemographic factors, exposure indicators, metrics of obesity, analytic methods, covariates, key associations and limitations. RESULTS: Of the 3007 records, 16 studies met the inclusion criteria. The findings suggest that climate-related factors, including natural disasters, rainy and wet seasons, longer daylight hours, extreme cold and rising temperatures, may be associated with increased risks of childhood overweight and obesity. However, the results remain inconsistent, varying across genders and locations. CONCLUSION: The review highlights the complex relationships between climate change and childhood obesity. Further research is needed to better understand the mechanisms and inform the development of climate adaptation strategies to reduce childhood obesity. PROSPERO REGISTRATION NUMBER: CRD42024560247.