Chronically high stress levels may partly explain why American black girls are more likely to be overweight than white girls.
That’s the chief finding of new research out of the University of California, Los Angeles.
The study, published in the Annals of Behavioral Medicine, found higher levels of stress over 10 years predict greater increases in body weight over time in both black and white girls. But chronic stress appears to have a greater negative effect on black girls' weight, which may be why the prevalence of obesity in black Americans is 50 percent higher than in whites.
Researchers noted the difference is apparent even in childhood, particularly in girls, and that minorities also tend to experience greater psychological stress than whites due, in part, to perceived racial discrimination.
"Our study documents a relationship between chronic perceived stress and [body mass index] over a decade of growth in black and white girls,” the authors concluded. “However, the relationship between perceived stress and BMI is stronger in black girls. Psychological stress may lead to weight gain through behavioral pathways, such as increased food consumption and sedentary lifestyles, but also directly through prolonged exposure to biological stress mediators such as cortisol."
For the study, researchers examined stress levels and BMI in 2,379 young black and white girls over a 10-year period – beginning when they were 10 years old – using data from the National Heart, Lung and Blood Institute's Growth and Health Study.
Over the course of the study, researchers found more black girls were overweight or obese than white girls, who reported more stress than black girls. In addition, levels of chronic stress predicted greater weight in both groups. Even though black girls reported less stress overall, the effect of chronic stress on weight was stronger for these girls.