We investigated associations of acculturation with various types of activity (moderate-vigorous leisure-time physical activity [LTPA], moderate-vigorous work- and transportation-related physical activity, and sedentary activity), and whether these activities mediated the acculturation-obesity association among Mexican-Americans.

Cross-sectional.

National Health and Nutrition Examination Survey (NHANES) 2007–2010.

Mexican-American NHANES participants aged ≥ 20 years (n = 1902).

Demographic characteristics, physical activity, sedentary behavior, acculturation, and body mass index.

Multinomial logistic regression was used to estimate associations of acculturation with categories of self-reported activity. Path analysis was used to test whether the activity measures mediated acculturation-obesity associations.

In adjusted models, compared to U.S.-born Mexican-Americans, foreign-born Mexican-Americans living in the United States for less than 10 years were significantly less likely to be in the highest LTPA and sedentary activity categories, and more likely to be in the highest total and transportation activity categories. Foreign-born Mexican-Americans living in the United States for 10 years or more were significantly less likely to engage in high sedentary activity but more likely to engage in high transportation activity. Sedentary behavior was the strongest mediator of the acculturation-obesity association, accounting for 40.7% and 57.1% of the total effect of acculturation on obesity among foreign-born Mexican-Americans living in the United States for less than 10 years and for 10 years or more, respectively, compared to U.S.-born Mexican-Americans.

Reducing sedentary behavior may lower the negative impact of acculturation on obesity.