From an article in the American Journal of Epidemiology:
Frequent experiences of racism were associated with a higher risk of obesity among African American women, findings from a recent study have demonstrated. These results suggest that the relationship between racism and obesity was strongest among women who reported consistently high experiences of racism over a 12-year period. The lead author suggests that work-place- and community-based programs to combat racism and interventions to reduce racism-induced stress could be an important component of strategies for prevention of obesity, especially in communities at high risk.
Ahh… that explains it.