In part four of a four-part series on the nation’s obesity epidemic, BU Today spotlights the innovative research taking place at BU to better understand and solve this health problem.
No population in the United States has a higher obesity rate than African American women, four out of five of whom are overweight or obese, according to a 2012 study by the Centers for Disease Control and Prevention. In the general adult population, 70 percent of adults are overweight or obese.
Julie Palmer (SPH’85) is trying to do something about the problem. Palmer, a senior epidemiologist at BU’s Slone Epidemiology Center and a School of Public Health professor of epidemiology, is a coordinator of the Black Women’s Health Study (BWHS), which has been tracking the health of 59,000 African American women since 1995. Along with looking for the reasons why diabetes, breast cancer, and glaucoma plague black women, her team has explored the root causes of their obesity and suggested realistic ways they can alter their lifestyles to lose weight.
“Our study is really trying to make a difference,” Palmer says. “It is pure research, but it is research with a heart. We want it to lead to changes in individual behaviors, changes in medical practitioners’ recommendations, and changes at the highest policy levels that will help all of us have better health.”
The initial BWHS calculated the women’s body mass index (BMI) and then every two years asked them about their weight and their consumption of soda and fast food, as well as their level of physical activity.
In 1995, the average age of participants was 38, and 30 percent were obese. Now, it’s more like 40 percent. Palmer finds that increase alarming, but it still doesn’t approach the national figure of 54 percent for all African American women. This may be because most women in the study have a college degree (61 percent) and aren’t as likely to be obese as are less educated women, according to the CDC.
The BWHS team combed through survey responses about diet and exercise to learn why the women struggled to maintain a healthy weight. “We found that even controlling for other things they ate, drinking a regular amount of sugar-sweetened sodas increased weight gain and increased the risk of obesity,” Palmer says.
And when the women were asked how often they ate out and what type of fast food they chose—burgers, pizza, Mexican, Chinese, fried chicken, or fried fish—those who frequently chose the first option had the most consequences. “We found that eating burgers from fast food or other restaurants definitely increased risk for obesity,” she says. “This was after controlling for soft drinks and after controlling for total fat. There’s something about red meat; we don’t know exactly what it is. And then there’s something about eating that type of meal and everything that goes with it. It was clearly worse than eating the fried fish, fried chicken, or the pizza.”
Palmer published their findings in biannual newsletters sent to study participants, with the recommendation that they substitute diet soda or water for regular soda and order pizza or Mexican, which has more nutrients and fewer calories than burgers. “We’re trying to identify things that people can actually do,” she says. “Because you can’t just say, ‘Lose weight,’ or, ‘Don’t eat so much.’ That’s really hard to do.”
When it came to exercise, women who vigorously worked out three or more hours a week had a much lower risk of becoming obese, Palmer says. But because not everyone has that option, the BWHS team also looked at the role walking plays in weight control. They found that women who did brisk walking and those who walked as a means of transportation had a lower risk of becoming obese than those who hardly walked at all. “That’s something people can do more easily,” she says. “They can build that into their day.”
Childbearing also proved a factor in weight gain. In a 2003 paper published in Nature, Palmer and her colleagues reported that African American women who have children young, are overweight at the time of pregnancy, or gain an excess amount of weight during pregnancy have a higher prevalence of obesity compared to white women.
And while they don’t have any results yet, the BWHS team is trying to learn if breast-feeding helps a woman “reset her metabolism” to decrease weight gain following pregnancy. The percentage of black infants who are breast-fed has shot up markedly in recent years, but it still lags compared to other groups. According to the CDC, 65 percent of black infants were breast-fed compared to 80 percent of Mexican American and 79 percent of white infants in 2005 and 2006. Palmer hopes her group’s research will encourage more black women to breast-feed and persuade policy makers to pass legislation facilitating breast-feeding in the workplace.
Psychological and social factors also have an impact. “Women who report more experiences of racism have been shown to be more likely to become obese,” Palmer says. About 55 percent of study participants reported experiencing discrimination at work, according to a July 2012 BWHS newsletter. Palmer also found that participants who live in disadvantaged neighborhoods—where grocery stores are scarce, parks and sidewalks aren’t maintained, or crime is rampant—often gained weight or were obese.
Several studies indicate that risk of death increases along with a person’s BMI, although it was widely believed that African Americans fared better than most at higher weights. That assumption, says Palmer, was based on limited data and was refuted by her team’s findings, which were published in 2011 in the New England Journal of Medicine, and showed that black women are equally disadvantaged by weight. They also found that women who carry more weight around their waists, although not considered obese, have a higher risk of death and diabetes.
BWHS participants often write to Palmer about positive changes they’ve made to reduce weight, and their comments are published anonymously in study newsletters. “B.C. orders water instead of soda whenever she eats out.” “D.H. stopped eating meat.” “R.S. says she’s cured of diabetes since she nixed everything white from her diet.”
Yet the relatively small-scale changes made by people in the study group are not going to make a dent in a national epidemic, Palmer says. What should be done? That, she says, is a tall order: children everywhere need to be taught healthy eating habits. Cities must clean up parks and quash violence to encourage physical activity. And urban planners should design more walker-friendly neighborhoods.
“We need to fund more small-scale or local-level efforts to help people make these changes in their lives,” Palmer says.
Read the entire series on fighting obesity here.