Effects of environmental factors on prevalence of obesity: A case study of immigrants

The rising rate of obesity is a great policy concern as it is associated with high health risks and hence high health costs. Obesity has surpassed tobacco as a leading cause of premature deaths in the United States (Jia & Lubetkin, 2010). Increase in obesity is concerning as it forms the breeding ground for chronic diseases such as diabetes, coronary diseases and hypertension. Obese men incur $1,152 and obese women incur $3,613 additional health care expenditures than a person of normal weight (Cawley &Meyerhoefer, 2012). An obese person earns almost 18% less and incurs 25% higher medical and health expenditures than a person of normal weight (OECD Obesity Report, 2012).

Immigrants offer a unique perspective into studying the effects of environment on obesity. According to the Healthy Immigrant Hypothesis, immigrants, on arrival, are healthier than the native population, but with the passage of time health status of these immigrants converges to that of the natives (Antecol and Bedard, 2006). Immigrants in the United States undergo a process of acculturation while being exposed to a new environment and social habits that causes them to adopt the life-style of the natives, which have an effect on their health.

This paper seeks to understand the effects of environment on obesity by studying the effect of acculturation on the health of a foreign population - who experience a relatively low prevalence of obesity - after they have been introduced to different environments, some are characterized by relatively low prevalence and others are characterized by relatively high rates of obesity.  Using the New Immigrant Survey data, this paper attempts to answer two questions. Could it be possible that the spread of obesity among immigrants vary by the regions in the new country?  Does acculturation- social and geographical - play a role in spread of obesity among immigrants?  Consider the thought experiment; would one expect an immigrant from South Korea to Mississippi, (obesity rate is 35%) to be affected differently than an otherwise similar immigrant from South Korea to Colorado (obesity rate is 21%)? The key assumption is that those factors that might lead to obesity are unrelated to those factors that affect the choice of region of residence in the US. The immigrants are unaware of the social and cultural conditions in the part of the country they are immigrating. The difference between the immigrants may be small before sorting. Hence, it can be argued that immigrants to a region are nearly randomized with regard to obesity prevalence in the surrounding.

 The estimates from a linear probability model show that after controlling for region fixed effects and for a number of acculturation variables, the immigrants residing in regions with higher percentage of obesity had a greater probability of higher BMI levels. Results also showed that women with higher degree of acculturation and higher duration of residence had lower probability of higher BMI levels.