The Role of Immigration Status and Residency Duration in the Risk of Obesity: Insights from an Adjusted Logistic Regression Analysis

Introduction: Obesity impacts about 42% of adults in the United States, affecting both U.S.-born and non-U.S.-born individuals, who comprise 14% of the population. This study investigates how migration status and residency duration influence obesity risk, adjusting for clinical, socioeconomic, and behavioral factors. Methods: Data from the 2017-2018 National Health and Nutrition Examination Survey (NHANES) were analyzed, including 5,591 adults aged 20 and older. Logistic regression assessed obesity, defined as a Body Mass Index (BMI) ≥30 kg/m², relative to migration status, with adjustments for age, gender, race, income, education, comorbidities, and behaviors. Results: Among 2,540 participants, 45.4% were classified as obese. Of U.S.-born individuals, 77.1% had a BMI ≥30 kg/m², compared to 40.9% of non-U.S.-born individuals. Non-U.S.-born individuals showed 46.2% lower odds of obesity (OR 0.54; p < 0.0001). In the adjusted model, foreign-born status was associated with 40% lower obesity odds (adjusted OR 0.6; p < 0.0001), though longer residency increased risk. Risk factors included female gender, Hispanic or Black race, higher income, and depression. Specifically, those residing in the U.S. for 15-20 years had 60% greater obesity odds (OR 1.62; p = 0.04), while over 20 years of residence saw an 88% increase (OR 1.88; p = 0.002). Conclusion: Migration status significantly influences obesity risk, with lower prevalence in non-U.S.-born individuals. However, longer U.S. residency heightens obesity risk, emphasizing the need for targeted public health strategies addressing cultural, socioeconomic, and dietary challenges faced by immigrants.