Time in the US tied to obesity—but only for some immigrant groups

Clinical takeaway: Consider time spent in the United States as one factor when discussing obesity prevention with foreign-born patients, recognizing that its association with obesity differs across racial and ethnic groups.

Previous studies have suggested that obesity becomes more common the longer immigrants live in the United States. This updated national analysis found that the pattern was seen in Hispanic and Asian adults, but not in White or Black immigrants. The findings suggest the relationship between time in the US and obesity is more complex than previously thought.

Researchers analyzed data from more than 22,000 foreign-born adults, representing an estimated 43 million US residents, who participated in the 2019 and 2021-2024 National Health Interview Survey. Overall, obesity prevalence remained lower among foreign-born adults than US-born adults, except among Hispanic immigrants who had lived in the United States for at least 15 years.

After adjustment for sociodemographic factors, foreign-born adults who had lived in the US for 15 years or longer had about twice the odds of obesity compared with those who had lived in the country for less than 5 years. This association was driven by Hispanic adults, who had about 2.7 times higher odds of obesity, and Asian adults, who had about 2.5 times higher odds. No significant association was observed among White or Black immigrants. The findings were unchanged after additional adjustment for health behaviors and healthcare utilization.

The study cannot determine why these differences exist. Potential contributors include differences in diet, physical activity, cultural factors, obesity risk before immigration, and changing immigration patterns over time.

“Our findings suggest that there are important racial and ethnic differences in the association between obesity prevalence and duration of US residence among foreign-born adults. Future research into the underlying contributors is needed to better target counseling and intervention efforts,” the study authors concluded.

Source: Claros M, et al. (2026 Jul 21) Ann Intern Med. Duration of U.S. Residence and Obesity Prevalence Among Foreign-Born Adults: Findings From the 2019 and 2021–2024 National Health Interview Survey