Black girls under 18 in America today are 80% more likely to be overweight than white girls. And while factors like healthcare and access to healthy food may play a role in the disparity, medical researchers have also begun to look into a less visible possibility: stress. Now a team has found that stress may indeed affect black and white girls differently — black girls report less of it, but it's more likely to cause them to gain weight.
For their study published in the Annals of Behavioral Medicine, psychologist A. Janet Tomiyama and her team looked at data collected on over 2,000 black and white girls over the course of 10 years, starting when they were 10 and continuing until they were 19. The data set included their height and weight, as well as responses to a standardized scale that measures stress through questions like, "In the last month, how often have you felt nervous and stressed?"
They found that the relationship between stress and weight gain was significantly stronger for black girls than for white girls. Previous research has shown a link between stress and weight gain, both because it makes people eat more and because it can cause their bodies to store fat differently, but Tomiyama's team found this link more pronounced in black girls than in white ones. Their study didn't specifically examine why, but they offer a couple of theories. They cited other research suggesting that eating more as a response to stress might be more common in black populations than white ones. And they noted that heavier people are more likely to gain weight in response to stress, while thinner people are more likely to lose it, and black girls were heavier on average than white girls at the start of the study.
It's also worth noting that race may affect how people's bodies store fat, and how it affects their health. Another study has found that exercise doesn't appear to prevent obesity in black teenagers as much as it does in white ones. And Tomiyama and her team note that obesity also appears less harmful to life expectancy in black women than in white women, possibly because black women tend to have a healthier distribution of fat in the body.
Although stress was more likely to lead to weight gain in black girls, they weren't actually more stressed than white girls — in fact, they reported less stress on average, over the course of the study. Tomiyama says that finding was especially interesting to her, because "it goes against a lot of what scientists think about many black individuals' experience — we are used to talking about the many stressors that black America faces, like racism [and] limited access to resources." For instance, another recent study found that racial discrimination can lead pregnant women to give birth to lower-weight babies, probably because it makes them depressed.
Tomiyama hopes to study the issue more, but she speculates that the difference may have to do with how white and black girls report their stress — black girls may indeed have experienced more stressful-seeming events (being discriminated against, or having a parent lose a job) than white girls have, but they may not feel as stressed by them. It's also possible that black girls are less likely to report stress they do feel. In the future, though, Tomiyama would like to examine whether black people are more "psychologically resilient" than whites — whether they are able to cope better or bounce back more quickly from stress.
Whatever the case, Tomiyama offers a couple of possible responses to the stress-weight gain link. She notes that researchers at UCSF are studying a treatment to curb stress-related eating that's based on mindfulness techniques. She also points out, though, that "stress doesn't just affect eating — it also tends to make people exercise less, sleep worse, feel depressed." These can all cause weight gain, and all are problems in their own right. "The best interventions," Tomiyama says, "will target all the different aspects of our lives that stress invades."