Since the 1980s, the U.S. population has become more obese, according to background information in the article. However, little information is available about the prevalence of obesity among immigrants, the fastest growing segment of the U.S. population, currently comprising more than 11 percent of the total U.S. population and an even larger proportion of many minority groups. Immigrants generally originate from countries where the prevalence of obesity is lower than that of the United States, but adopting U.S. norms over time may lead to an increasing prevalence of obesity among this population.

Mita Sanghavi Goel, M.D., M.P.H., of the Feinberg School of Medicine, Northwestern University, Chicago, and colleagues examined the relationship between prevalence of obesity and years of U.S. residence among immigrants nationally, and explored whether counseling about diet and exercise may differ between immigrants and U.S.-born adults. The researchers used data from the 2000 National Health Interview Survey. Information collected included body mass index (BMI, measured as weight in kilograms divided by the square of height in meters) and rates of diet and exercise counseling.

Of 32,374 respondents (representing an estimated 201 million adults in the United States), 14 percent were immigrants. The prevalence of obesity was 16 percent among immigrants and 22 percent among US-born individuals. The researchers found that the prevalence of obesity was 8 percent among immigrants living in the United States for less than 1 year, but 19 percent among those living in the United States for more than 15 years. After adjusting for age, sociodemographic, and lifestyle factors, living in the United States for 10 to 15 years was associated with a BMI increase of 0.88, while living in the United States for at least 15 years was associated with a BMI increase of 1.39. The association for more than 15 years was significant for all immigrant subgroups, including whites, Latinos and Asians, but not foreign-born blacks. To illustrate the impact, for a typical 5 ™4 immigrant woman and a typical 5 ™9 immigrant man this amounts to an excess 9 lb. (4.05 kg) and 11 lb. (4.95 kg), respectively, in addition to any weight gained due to aging or other factors, the authors write.

The study also found that immigrants were less likely than U.S.-born individuals to report discussing diet and exercise with clinicians (18 percent vs. 24 percent; 19 percent vs. 23 percent, respectively).

In summary, immigrants appear to assume a similarly high prevalence of obesity as U.S.-born adults with longer duration of residence. With the growing immigrant population in the United States, early clinician intervention on diet and physical activity may represent an important opportunity to prevent weight gain, obesity, and obesity-related chronic illnesses, the researchers conclude.

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