A new study hypothesizes that the detrimental effects of chronic stress may have an ethnic bias.
UCLA researchers believe that experiencing high levels of stress (for a decade or more), influences body weight increases in both black and white girls.
However, the experience of chronic stress appears to have a greater negative effect on black girls’ weight, which may explain racial disparities in obesity levels, said lead author Dr. A. J. Tomiyama.
Tomiyama and team looked at whether the experience of chronic stress in young girls over a 10-year period might have an effect on Body Mass Index (BMI), a measure of obesity. They also assessed if this effect might be different in white and black teenage girls.
In the U.S., the prevalence of obesity in black populations is 50 percent higher than in whites. This difference is found even in childhood, especially among female adolescents. In addition to the stress associated with obesity, ethnic minorities may experience stress related to perceived racial discrimination.
Researchers used data from the National Heart, Lung and Blood Institute’s (NHLBI) Growth and Health Study, to determine the prevalence of obesity in 2,379 black and white girls beginning at age 10. They then followed the girls for 10 years, evaluating weight and their experience of psychological stress over that time.
Over 10 years, 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 with one unit increase in stress leading to 0.8 BMI unit increase every two years.
Comparatively, one unit of stress led to 0.55 BMI unit increase in white girls.
The authors conclude: “Our study documents a relationship between chronic perceived stress and BMI over a decade of growth in black and white girls. However, the relationship between perceived stress and BMI is stronger in black girls.”
Researchers said psychological stress may lead to weight gain in a variety of ways. Directly, stress may cause people to eat more and have lower levels of physical activity. Stress may also activate biological stress mediators such as cortisol which can cause weight gains.
Researchers believe stress may be fueling the obesity epidemic among young children and adolescents. Minorities may have significant challenges as they battle stress-induced obesity as well as stress associated with racial discrimination.
The study is published online in the journal Annals of Behavioral Medicine.