Introduction Greater time in the USA has been associated with a higher risk of obesity among immigrants. Few studies have examined this pattern longitudinally or considered measures of the neighbourhood environment in evaluating weight-related change among immigrants the longer they live in the USA.

Methods Using prospective data from 883 Hispanic and 688 Chinese foreign-born subjects aged 45–84 in the Multi-ethnic Study of Atherosclerosis, we used linear mixed models to examine whether neighbourhood environments characterised by greater healthy food availability and greater walkability are associated with baseline waist circumference (WC) and with change in WC over a median follow-up of 5 years.

Results Neighbourhoods were characterised using survey items; higher scores represented better environments. Adjusting for age, sex, education, income, years lived in the US at baseline, and neighbourhood poverty, among Hispanics, only greater healthy food availability was associated with lower mean baseline WC (mean difference per SD higher neighbourhood score=−0.98 cm, p=0.028). There was no association between neighbourhood context and WC change over time. Among Chinese, greater walkability was associated with lower mean baseline WC (β=−1.06 cm, p=0.007) and with smaller increases in WC over time (mean difference in annual change per SD higher walkability=−0.12 cm, p=0.003). Associations with walkability also differed for long-term vs more recent immigrants among Chinese. (p heterogeneity=0.001) (effect modification by baseline length of US residence)

Conclusion Where immigrants reside may have implications for the health patterns that emerge with greater time in the USA.