Extra weight around the middle raises risk for more than just cardiovascular disease, cancer and diabetes. It also increases the chances of developing asthma, according to a team of California researchers.
The findings, published in the September issue of Thorax, draw data from the California Teachers Study, which is led by Leslie Bernstein, Ph.D., director of City of Hope’s Division of Cancer Etiology. Bernstein was a co-author on the study.
The California Teachers Study includes nearly 133,500 female teachers and administrators in the California public schools’ retirement system. Researchers began following the women in 1995, periodically asking them about their health and health-related factors including diet, exercise and medication use.
Scientists studied 88,304 women from the study for the asthma project. Out of these women, 11,500 were obese at the study’s start and 1,334 were very obese. The researchers examined who had developed adult-onset asthma and who did not.
Compared to women of normal weight, women who were obese had double the likelihood of having adult-onset asthma. Extremely obese women were more than three times as likely to have asthma. And even being moderately overweight increased asthma risk, the authors noted.
Weight only tells part of the story, though. Women with a normal BMI had an increased risk of asthma if they had a large waist measuring more than 88 centimeters or nearly 35 inches around.
Overweight and obese women also had a greater risk of dangerous asthma attacks: episodes severe enough to send them to the emergency room or get urgent medical attention.
“These findings are particularly troubling because a majority of American adults are now overweight or obese,” authors wrote. Experts estimate that 66 percent of Americans fall into one of these categories.
Many Americans carry that fat around the middle. Some 61 percent of American women are “abdominally obese” based on waist circumference, according to data from the 2003-04 National Health and Nutrition Examination Survey. Fat carried around the middle, also called visceral fat, is thought to be more biologically active and may encourage more inflammation in the body, although more study is needed to understand the mechanisms behind the increased risk.
The study’s lead author, Julie Von Behren, Ph.D., is from the Northern California Cancer Center. Collaborators include scientists from the Keck School of Medicine of the University of Southern California, the California Department of Public Health and the University of California, Irvine.