摘要：Objectives. We investigated whether race differences in weight gain over 34 years were because of socioeconomic position (SEP) and psychosocial and behavioral factors (physical activity, cigarette smoking, alcohol consumption, depression, marital status, number of children). We used a life-course approach to SEP with 4 measures of SEP (childhood SEP, education, occupation, income) and a cumulative measure of SEP. Methods. We used mixed models and data collected from the Alameda County Study to examine the association between race and weight change slopes and baseline weight in men (n=1186) and women (n=1375) aged 17 to 40 years at baseline (in 1965). Results. All subjects gained weight over time. African American women weighed 4.96 kg ( P < .001) more at baseline and gained 0.10 kg/year ( P = .043) more weight than White women. Black men weighed 2.41 kg ( P = .006) more at baseline but did not gain more weight than White men. The association of race with weight gain in women was largely because of cumulative SEP score. Conclusions. Interventions to prevent overweight and obesity should begin early in life and target the socioeconomically disadvantaged. Rates of obesity and overweight in the United States have continued to rise over several decades. 1 – 3 Although all racial and ethnic groups are experiencing this trend, obesity is more common in Black than in White Americans, with this difference being particularly large among women. 4 Several longitudinal studies have found African Americans to be at greater risk of adult weight gain than Whites, with the racial/ethnic differences being stronger and more consistent in women. 5 – 8 Lower socioeconomic position (SEP) has been shown to be associated with obesity. 9 Because Blacks are more likely to experience lower SEP than Whites, it is plausible that observed racial differences in body weight might be because of socioeconomic disadvantage. Studies investigating the role of SEP in explaining racial differences in weight gain have included adjustments for 1 or at most 2 measures of SEP. 6 , 7 In these studies, the racial difference in weight gain was attenuated but not eliminated. We examined racial/ethnic differences in weight gain by measuring body weight in a community sample over a 34-year period, a period that covered most of the adult lives of many of the participants. Studies have shown that long-term weight gain in adulthood is associated with a greater risk of coronary heart disease, 10 breast cancer, 11 and insulin resistance syndrome. 12 Most of the previous prospective studies of racial/ethnic differences in weight gain were conducted over much shorter periods of time (5 to 10 years). 6 – 8 We took a life-course perspective when examining SEP as a mediator of racial differences in weight gain. Such a perspective recognizes that socioeconomic exposures during the life course may independently contribute to weight gain, or exposures may be linked to each other and accumulate over time. 13 , 14 To our knowledge, this study of racial/ethnic differences in body weight is among the first to take such a life-course approach and to include multiple measures of SEP (childhood SEP, education, occupation, and income). We explored the measures of SEP separately and then used them to create and investigate a measure of cumulative socioeconomic disadvantage. Psychosocial factors and behavioral factors independent of SEP also may explain the racial difference in body weight, but little research has examined such factors as mediators of racial/ethnic differences in body weight. We also examined the roles of marital status, the number of children in the household, physical activity, smoking, alcohol consumption, and depression as possible mediators of racial differences in weight gain. We hypothesized that Blacks would have a greater rate of weight gain than Whites. We also hypothesized that the racial differences would largely be because of SEP, especially as measured by cumulative SEP. Finally we hypothesized that any remaining racial difference in weight gain would be explained by psychosocial and behavioral variables.
