There's new proof that American dietary habits aren't good for the waistline. A study recently published in the Journal of the American Medical Association reveals that immigrants who've been in the United States for a number of years are fatter than those who recently arrived. VOA's Maura Farrelly reports.

As Americans have become bigger, and the negative health effects of obesity have become more apparent, medical researchers in the United States have turned their attention to the topic of why people are fat. So far, most studies have considered only the native-born population. But for Mita Sanghavi Goel (GOIL), a medical professor at Chicago's Northwestern University, her study of immigrants and obesity was prompted, in part, by her own family.

Just in looking at my own family, my parents are immigrants, and when I looked at their wedding pictures and then looked at them, I sort of wondered, Something has changed. That might be true in many, many families, but I thought about that in the context of an immigrant lifestyle in the United States.

For newly-arrived immigrants, obesity is not a major problem - just 8 percent are obese, compared with 22 percent of native-born Americans. But after a number of years, the immigrant population starts to look a lot more like the native-born. Dr. Goel found that among immigrants who've been in the United States for 15 years or more, the obesity rate was 19 percent- almost as high as the native population.

We found that this was true for foreign-born whites, foreign-born Latinos, and foreign-born Asians. We didn't see this association for foreign-born blacks, and it could be we just didn't have a large number of foreign-born blacks in our population.

So what's causing this? Dr. Goel's study didn't attempt to answer that question, but she and others in the medical community say it isn't too difficult to figure out. There's a lot of food to be had in the United States, and much of it is processed and full of fat and sugar.

As people move to this country, there's certain foods that are more readily available.

Dr. Alan Tso (CHO) is a physician who works with immigrants at the Charles B. Wang Community Health Center in New York City's Chinatown.

It's very different from some of the villages in China. And so meat is more readily available and so on and so forth. So a lot of immigrants, [when] they come over, they change their diet habit. (0:12)

They also change the way they eat, according to Xiao bin Li, an immigrant who's been living in the United States for almost fifteen years. Ms. Li says in China, most people eat their main meal in the middle of the day, and then have a light dinner before going to bed. But in America, people are working too much during the day to eat a major meal.

So that's why [you] eat just a small lunch. But after a whole day of work, when you go home, you want a big dinner. After dinner, you only lie down, then sleep. No exercise or something.

It's not clear that immigrant communities recognize that excess weight is a problem. Researcher Mita Goel says very few immigrants visit a doctor about their weight, and Dr. Alan Tso says this may be because of cultural misconceptions about chubbiness.

Again, it goes back to economics, basically. You know, people who are more well-off, in China, at least, in the old days, you know, they have a rounder face, because they eat better, right? That's the symbol of wealth.

Dr. Tso says this misconception is having an impact on children. He recently completed s study of more than 300 children, all born to immigrants living in the United States. And he found the youngsters were more likely to be obese if they'd been born after their parents had arrived in America.