Race, education, and weight change in a biracial sample of women at midlife.

BACKGROUND: Overall rates of obesity have increased dramatically in the United States, yet African American women remain disproportionately represented among the overweight and obese. The excess weight observed in African American women is primarily considered a result of low socioeconomic status, but recent cross-sectional findings suggest otherwise.

METHODS: We examined the interactive effects of race and 3 levels of education (low [high school or less]; moderate [some college]; and high [college degree or more]) on body mass index (BMI) (calculated as weight in kilograms divided by the square of height in meters) and changes in BMI over 4 years in 2019 middle-aged African American and white women from the Study of Women's Health Across the Nation (SWAN). Data were analyzed with mixed effects regression models.

RESULTS: At baseline, we observed a significant race x education interaction (estimate, -3.7; 95% confidence interval, -5.3 to -2.1; P<.001) on BMI. Compared with whites, African Americans had higher BMIs, but only at the moderate (means, 32.1 and 29.2) and highest (means, 31.5 and 27.8) level of education. At the lowest level of education, African American and white women were similar in BMI (means, 31.1 [African American] and 31.2 [white]). Body mass index increased significantly for all women over follow-up (estimate, 0.22; 95% confidence interval, 0.17 to 0.26; P<.001), but increases did not differ by race, education, or race x education. Results were unchanged after adjustment for potential confounding variables.

CONCLUSIONS: For middle-aged women, racial disparities in BMI are largely patterned by education, with the greatest disparities observed at higher levels of education. The absence of significant longitudinal effects suggests that these race-education patterns are set in place and well established before midlife.