Differential effect of food security on BMI by birthplace and years of residence in the United States among women in California

BACKGROUND/SIGNIFICANCE: Although cross-sectional studies have found that female adults in food insecure households have a higher prevalence of overweight/obesity (BMI≥25), few studies have examined whether effects of food security on BMI are different for foreign born compared to US born women.. OBJECTIVE/PURPOSE: To determine the relationship between food security and overweight/obesity, and whether this relationship varies according to birthplace-US length of residence among women in California. METHOD: Using data from California Health Interview Survey (CHIS) years 2001, 2003, and 2005, prevalence of overweight/obesity according to birthplace-US length of residence was estimated; regression models were fitted that controlled for age, marital status, income, education, birthplace, years of residence in US, smoking, physical activity, diabetes, and an interaction term between food security and birthplace was added. Food security was measured as a 2-way categorical variable. To avoid collinearity, birthplace and years of residence in the US were combined into a single variable as follows: US born, Foreign born>10 years of residence, and Foreign born<10 years of residence. RESULTS: The relationship between BMI and food security was statistically significant (p≤0.001) after controlling for age, race, marital status, income, education, birthplace, years of residence in the US, smoking, physical activity, and diabetes. Additionally, we found that the relationship between food security and BMI was statistically significantly different (p=0.014) for U.S. born compared to foreign-born women. DISCUSSION/CONCLUSION: Since the relationship between food security and BMI varies according to birthplace-US length of residence, future studies should examine this relationship among women of specific ethnic groups.