To estimate associations between the length of residence and overweight among US immigrants by region of birth and age at arrival.

Cross-sectional data from the National Health Interview Survey 1997–2005 were pooled. Multivariate-adjusted prevalence and OR were computed to test associations of length of residence and overweight.

United States.

Immigrant adults aged 18–74 years.

The odds of being overweight were three times higher in migrants from Mexico, South America, Europe, Russia, Africa and the Middle East residing in the US for >15 years than their counterparts residing in the United States for <5 years. On the other hand, migrants from the Indian subcontinent and Southeast (SE) Asia had no association between the length of residence and overweight prevalence. Among both men and women, weight differences emerged as early as 5 years after arrival among those arriving at 18–24 years of age (OR 1·5–1·8). The odds of being overweight was higher among Hispanic men arriving before the age of 18 years than the European migrants (Mexico OR 1·7, 95 % CI 1·3, 2·2; South America OR 1·5, 95 % CI 1·0, 2·3), whereas the odds of being overweight among those from Africa and SE Asia was lower (OR 0·5, 95 % CI 0·3, 0·9 and OR 0·5, 95 % CI 0·4, 0·8, respectively). Among women who arrived at 25–44 years of age, the odds of being overweight among those from Africa and the Indian subcontinent was higher than the European migrants (OR 2·9, 95 % CI 1·7, 5·0 and OR 1·8, 95 % CI 1·8, 2·8, respectively).

We found associations between the length of residence and overweight to vary by region of birth and age at arrival, highlighting the importance of these characteristics in assessing overweight risk among the US immigrants.