Association between Age at Arrival, Duration of Migration, and Overweight/Obesity in Chinese Rural-to-Urban Migrants: The Yi Migrant Study
Introduction Overweight and obesity have become global health challenges, with rising prevalence observed in both developed and developing countries. These conditions contribute significantly to the burden of obesity-related illnesses. While genetic factors play a role in obesity, environmental factors such as lifestyle changes are also critical contributors. In China, rapid urbanization has led to a large-scale migration of rural populations to urban areas, yet the association between this migration and the risk of overweight/obesity remains understudied. This study focuses on the Yi people, an ethnic minority in China, to explore how age at arrival and duration of migration influence the risk of overweight and obesity among rural-to-urban migrants.
Background and Objectives The Yi people, primarily residing in remote mountainous regions of southwest China, have traditionally maintained a rural lifestyle. However, since the 1950s, many Yi individuals have migrated to urban areas, adopting new lifestyles. Previous studies have highlighted disparities in non-communicable disease risks between Yi farmers and Yi migrants, but the relationship between migration and overweight/obesity remains unclear. This study aims to evaluate the risk of overweight/obesity in Yi farmers and Yi migrants, and to examine how age at arrival and duration of migration are associated with this risk. The hypothesis is that Yi migrants have a higher risk of overweight/obesity compared to Yi farmers, and that age at arrival and duration of migration are significant factors influencing this risk.
Methods This cross-sectional study was conducted in 2015 in Sichuan Province, China, involving 3056 Yi individuals aged 20 to 80 years, including 1894 Yi farmers and 1162 Yi migrants. Data on demographic characteristics, lifestyle factors, and anthropometric measurements were collected. Body mass index (BMI) was calculated, and overweight/obesity was defined as a BMI of 25 kg/m² or higher. Duration of migration was categorized into 1–10, 11–20, 21–30, and over 30 years, while age at arrival was classified as 0–20 years and over 20 years. Statistical analyses included general linear regression models to assess the effect of migration on BMI and multivariable logistic regression to examine the association between migration duration and overweight/obesity.
Results The study found that Yi migrants had a significantly higher mean BMI (24.48 kg/m²) compared to Yi farmers (22.28 kg/m²). After adjusting for age, sex, and other confounders, Yi migrants had a 1.71 kg/m² higher BMI and a 2.13-fold higher risk of overweight/obesity than Yi farmers. The risk of overweight/obesity increased with longer duration of migration, particularly among those who migrated at an older age. Specifically, migrants who arrived in urban areas over the age of 20 and had lived there for more than 30 years had a 1.85-fold higher risk of overweight/obesity compared to those with 1–10 years of migration. However, no significant association was observed among those who migrated at a younger age (0–20 years).
Discussion The findings align with previous studies that have shown a positive association between duration of migration and overweight/obesity, both in international and domestic migration contexts. The increased risk among Yi migrants can be attributed to lifestyle changes, such as reduced physical activity and unhealthy dietary habits, which are common in urban environments. Socioeconomic factors also play a role, as migrants with longer urban residence tend to have higher education and income levels, which may lead to more sedentary lifestyles and greater access to high-calorie foods. The study highlights the importance of considering age at arrival when assessing the health impacts of migration, as older migrants may be more susceptible to weight gain due to lifestyle changes.
Conclusion This study underscores the higher risk of overweight/obesity among Yi migrants compared to Yi farmers, with the risk increasing with longer duration of urban residence, especially for those who migrated at an older age. These findings call for targeted public health interventions to promote healthy lifestyles among rural-to-urban migrants, particularly those who migrate later in life. Future research should explore the specific dietary and physical activity changes associated with migration and their impact on obesity risk.
doi.org/10.1097/CM9.0000000000000973
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