Obesity and the experienced cultural, economic and climate variations among immigrants to high-income countries: An umbrella review of the literature

OBJECTIVE: Obesity is a growing global public-health concern, particularly among immigrants to high-income countries. This umbrella literature review synthesizes evidence from systematic reviews to explore the multifactorial cultural, socioeconomic and environmental determinants of obesity and weight gain among immigrants to high-income countries. DESIGN: A systematic search of PubMed, Web of Science, and Scopus was conducted from January 2015 to November 2025 to identify systematic reviews and meta-analyses examining the impact of cultural, socioeconomic, and environmental factors on obesity among adult immigrants (i.e., economic, students, and refugees) to high-income countries. SETTING: 33 reviews were included and thematically synthesized under four domains: physical climate and physiological changes, socioeconomic stressors and psychological mediators, cultural factors, and methodological quality - rated using the AMSTAR tool. RESULTS: The review found consistent evidence linking longer duration of residence and higher levels of acculturation with increased obesity risk. Socioeconomic disadvantage, food insecurity, and psychological stress-particularly acculturation stress-were key mediators of weight gain. Less sunny colder climates impacted on weight gain indirectly through limiting physical activity and accessibility to traditional-healthy diet outlets. Cultural dietary transitions and intergenerational differences further influenced obesity trajectories. Methodological quality varied, with only six reviews providing meta-analysis pooled estimates of obesity and being rated as high to moderate quality. CONCLUSIONS: Obesity among immigrants is shaped by intersecting cultural, socioeconomic, environmental and physiological factors. Public-health strategies must adopt culturally sensitive approaches that address structural barriers and support healthy transitions post-migration. Future research should emphasise longitudinal, intersectional, and climate-tailored studies to inform targeted interventions.