Study: Stress a weightier problem for black girls
Researchers now want to know what causes racial disparity
We know that the country is facing an epidemic of obesity-related chronic diseases in young people. We also know from studies (as if we parents need studies) that the level of stress and anxiety teens face is at an all-time high.
I talked to Janet Tomiyama, an assistant professor of psychology at UCLA, about research she and her colleagues recently completed looking at how perceptions of stress affect weight gain in adolescent black and white girls over a decade.
The main finding was that although stressed-out black girls and white girls tend to gain weight, stress appears to have a greater effect on the weight of black girls. But the kicker is that black girls reported less stress overall than white girls.
Why the disconnect? It's not exactly clear, but Tomiyama said researchers are exploring some ideas, which I'll get to in a minute.
Tomiyama and her team undertook the study because, though there's a lot of research looking at the black-white disparity in obesity in adults, there isn't much addressing what's happening with younger people, especially girls.
"The biggest (gap) in health disparities in this country is in the obesity rates between black and white teen girls," she said.
According to a recent report, "F as in Fat: How Obesity Threatens America's Future 2012," whites in Illinois have an overall obesity rate of 26 percent compared with the black rate of 39.2 percent. It's not clear what the obesity rates are for adolescents in Illinois.
But Tomiyama said many of the obesity disparities are seen as early as childhood, particularly in adolescent girls.
This study, published online in the Annals of Behavioral Medicine, was conducted by examining data from a long-term study by the National Heart, Lung and Blood Institute that began in the 1980s.
The Growth and Health Study looked at 2,379 girls, half of them black and half of them white. The girls, who lived in California, Washington, D.C., and Ohio, came from homes of varying income levels. Researchers wanted to understand why there was such a racial disparity in obesity rates in adult women, and they started by looking at 10-year-old girls and following them until age 19.
Tomiyama said one aspect that's unique about her research and team, which is composed of psychologists rather than medical doctors, is that they're exploring stress — and not just poor eating habits and lack of exercise — as a significant component of weight gain. She said it's a relatively new field of study.
"It's a new push to say that our emotions are not just fluffy things that don't matter," she said. "They have concrete effects in our daily lives and they affect our health. This isn't just about a lack of willpower. There's a good reason why we want mashed potatoes when we're stressed. It's comforting."
What is not known, however, is why black girls perceive stress differently and why they're gaining more weight than white girls. The research showed that in black girls, a one unit increase in stress led to a 0.8 increase in body mass index every two years. One unit of stress led to 0.55 BMI unit increase in white girls.
Tomiyama said one possible answer may have something to do with the stress hormone cortisol. When we're stressed, we produce more cortisol, which makes the body deposit fat in our belly regions. Tomiyama said researchers will next try to determine whether black girls are under more stress and producing more of the hormone — even if they don't think they're stressed.
Researchers had believed that prejudice and discrimination might be an added stressor for black girls.
"But when black girls reported less stress overall (than the white girls), we were surprised by that," Tomiyama said. "So the next step is to measure what black girls report (in terms of stress) and compare that to stress hormones" to see if there's a disconnect.
She said comfort-eating as a coping behavior is another area to examine. Also, people sometimes postpone exercise when they're stressed.
The girls from the Growth and Health Study are now 33-year-old women. Tomiyama said that next year, she and her colleagues hope to get funding to begin looking at the California group of about 620 women to see what has changed over the years. So far, researchers have contacted about 100 women, the majority of whom have children.
"We want to know if there's intergenerational transmission of obesity," she said.
So, I wondered, what about studies that show black girls tend not to worry as much as white girls about being super thin? Might some of that extra worrying come from one group feeling more stressed about overeating than the other group?She said that and more will be on the table for a possible follow-up study.