Helen P. Hazuda, Ph.D.
Previous studies have found significant cross-sectional associations of acculturation and socioeconomic status (SES) with obesity in Mexican Americans (1, 2). This paper examined whether sociocultural status also predicts weight gain or increased body mass index (BMI) in Mexican American adults, ages 25 ? 64 years old. Data are from the San Antonio Heart Study (SAHS), a population-based study of diabetes and cardiovascular disease in Mexican Americans (MA) and European Americans (EA). Subjects were enrolled in the baseline exam in two phases, from 1979-82 and 1984-88, and in a follow-up exam approximately 8 years later, from 1987-91 and 1992-96. Of the 5158 subjects who completed the baseline exam, 163 died before the follow-up began; 3,683 completed the follow-up exam for a response rate of 73.7%. Response rates were nearly identical in the two ethnic groups. While non-responders were about four years younger compared with responders, there was no difference between these two groups in baseline BMI, weight, level of schooling, or level of household income.
Six obesity outcomes were calculated: BMI and weight at follow-up, and absolute change and percent change in BMI and weight from baseline to follow-up. Prevalence and incidence of overweight (bmi > or = 25 and < 30) and obesity (bmi > or = 30) were also examined. Three dimensions of acculturation were measured using the previously published Hazuda acculturation and assimilation scales: functional integration with the broader society (Functional Integration), value placed on preserving Mexican cultural origins (Cultural Values), and attitude toward traditional family structure and sex-role organization (Family Attitude) (3). Education, household income, occupation, and the composite Duncan Socioeconomic Index were used as indicators of socioeconomic status (SES). Data were analyzed separately for men and women using multiple regression with baseline age and bmi or weight as covariates.
Prevalence of obesity and overweight was high in both ethnic groups and both sexes. At both baseline and follow-up about 50% of men and 30% of women were overweight, while 20-26% of men and 15-42% of women were obese. Among the four sex-ethnic subgroups European American women had the lowest prevalence of overweight and obesity. Incidence of overweight and obesity were: MA men -- 12.8 and 11.0%, respectively; MA women ? 15.2 and 12.7%, respectively; EA men ? 13.9 and 11.2%, respectively; and EA women ? 17.1 and 9.5%, respectively.
Among Mexican American men, Functional Integration, education and income were consistently and significantly associated with weight and weight change at follow-up but not with BMI. Somewhat unexpectedly, higher levels of sociocultural status at baseline were associated with higher BMI and greater increases in weight at follow-up. For example, each higher level of Functional Integration was associated with about a 1-1/2 lb. increase in weight. Among Mexican American women, none of the acculturation or SES measures were consistently associated with weight or with weight or BMI changes at follow-up. While all of the sociocultural indicators were significantly and negatively associated with follow-up BMI, these associations became negligible and non-significant after adjustment for baseline BMI. In both MA sex groups, baseline BMI and weight accounted for 70-77% of the variance in BMI and weight at follow-up.
Three possible mediators of the association of sociocultural status with weight and weight change at follow-up were examined: weekly frequency of planned exercise, efforts to lose or control weight by exercise, and efforts to lose t or control weight by dieting. All three possible mediators were positively associated with weight gain at follow-up. However, efforts to lose or control weight by exercise was consistently and significantly associated with weight gain indicators, and appeared to be the primary mediator of the association between sociocultural status and weight gain in MA men.
These findings from the SAHS suggest that interventions to help people maintain or restore normal weight should be targeted toward MAs (and EAs) at all levels of sociocultural status. Normal weight persons of high sociocultural status, most demonstrably MA men, would benefit from preventive interventions to reduce their risk of incident overweight and obesity. Further research is needed to understand the dynamics underlying individuals? efforts to lose or control weight by dieting, particularly among MA men.
Several study limitations should be noted. First, there was a 7-8 year time interval between baseline and follow-up measures. Second, change in mediators over time was not measured in relation to change in weight, although sociocultural status remained more or less stable over the time interval examined. Third, no performance measures of physical activity were collected, and other lifestyle mediators were assessed by single- or two-item measures. Finally, present analyses did not include available measures of dietary intake.
- Hazuda HP, Haffner SM, Stern MP: Effects of acculturation and socioeconomic status on obesity and diabetes in Mexican Americans: the San Antonio Heart Study. American Journal of Epidemiology 128:1289-1301, 1988.
- Hazuda HP, Mitchell BD, Haffner SM, Stern MP: Obesity in Mexican American Subgroups. American Journal of Clinical Nutrition 53:1529S-34S, 1991.
- Hazuda HP, Stern MP, Haffner SM: Acculturation and assimilation among Mexican Americans: Scales and population-based data. Social Science Quarterly 69(3):687-705, 1988.