Bad news for new Americans: A study published today shows that simply moving to the USA packs on the pounds.
''The longer you live here, the more likely you are to be obese,'' says Mita Sanghavi Goel, a doctor at Northwest University in Evanston, Ill., and lead author on the study.
The study published in today's issue of the Journal of the American Medical Association examined obesity rates among immigrants and native-born Americans. It found that living in the USA for more than 15 years was associated with a 1.39 increase in body mass index, a scientific measure for weight.
The National Institutes of Health defines a normal-weight BMI as 18.5 to 24.9.
At least three previous studies have found similar increases by comparing immigrants with their children born in the USA. But this is the first study that examines the weight gain among immigrants over an extended time.
This is a new facet of the nation's obesity problem. Government data show that about 65% of Americans are either overweight or obese. Experts fear an explosion of diabetes, heart disease, cancer and other illnesses associated with obesity.
In general, immigrants are healthier than native-born Americans, Goel says: ''They have lower rates of heart disease and overall lower rates of diabetes.''
The BMI increase doesn't start until after 10 years in the USA, probably because it takes that long for new immigrants to become immersed in the American culture, according to the study. But after 15 years, the prevalence of obesity among immigrants approaches that of U.S.-born adults.
The study found the same change for immigrant whites, Latinos and Asians. There weren't enough foreign-born blacks in the study for a finding, Goel says.
She believes the weight gain occurs because of changes in diet and ways of living. Previous research has shown that immigrants tend to consume less fat and sugar, probably because they eat fewer prepared and processed foods.
But as they become more Americanized, the newcomers eat fewer fruits and vegetables and more processed foods, meat and sugar.
One prime motivator pushing immigrants toward a more American and less healthy diet is children, says Patricia Crawford, co-director of the Center for Weight and Health at the University of California-Berkeley.
''We have very aggressive marketing to kids, and the kids begin lobbying the moms,'' says Crawford, whose center has extensively studied immigrant diets. ''In focus groups among young Latina mothers, we hear about the pressure from their kids to be American and eat American, and the whole family changes what it eats.''
Immigrants also exercise much less. At home they might have walked long distances, something that's often impossible in American cities, she says.
Of course, that's in part why they came to the USA, she says, ''a lifestyle that has these resources -- cars, televisions -- but it's not necessarily a lifestyle that's more healthy for them.''
Also, the poorer neighborhoods in which many new immigrants live often have supermarkets that are not well stocked with healthful foods, or there are no supermarkets at all. The neighborhood convenience stores tend to stock mostly processed foods, Crawford says.
Immigrants also are less likely to receive dietary counseling than U.S.-born patients, Goel says. For example, Goel says, her immigrant mother-in-law is a diabetic. ''She was doing a good job of cutting down on bread, but it took her a while to realize that she also should be cutting down on rice. So you have to have culturally appropriate counseling.''
The good news is that one way to protect immigrants from calorie creep is simply to encourage them to maintain their traditional diets, Goel says.
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