Air pollution may lead to weight gain, obesity in women

ANN ARBOR, Mich. — Make no mistake, obesity is a global problem. On a worldwide scale, obesity rates have tripled since 1975. Expanding waistlines are especially prevalent in the United States, with more than four in 10 adults meeting the criteria for obesity. While there are a number of factors behind this troubling trend, a new study finds air pollution may be yet another element tipping the scale toward obesity — at least for certain women.

Scientists at the University of Michigan report middle-aged women exposed to smog may be more likely to experience weight gain and develop a higher body mass index, a larger waist circumference, and more body fat. A group of older, middle-aged women who experienced long-term exposure to air pollution tended to gain more weight, study authors say.

“Women in their late 40s and early 50s exposed long-term to air pollution — specifically, higher levels of fine particles, nitrogen dioxide, and ozone — saw increases in their body size and composition measures,” reports first study author Xin Wang, an epidemiology research investigator at the U-M School of Public Health, in a university release.

These findings are based on a dataset of 1,654 Caucasian, Black, Chinese, and Japanese women who had participated in the Study of Women’s Health Across the Nation. Researchers tracked all of those participants, whose baseline median age was close to 50, between 2000 and 2008.

Meanwhile, study authors determined annual exposure to air pollution by linking residential addresses with hybrid estimates of air pollutant concentrations. Then, the research team analyzed any and all associations between local air pollution levels and each participants’ body size and composition measures. One question in particular they wanted to clarify: Does exercise influence these associations?

The air you breathe could add over 2 pounds

Ultimately, the team at UM discovered air pollution exposure displayed a link to higher body fat, higher proportion fat, and lower lean mass among midlife women. For example, body fat increased by 4.5 percent (roughly 2.6 pounds).

Study authors were also sure to explore interactions between air pollution and physical activity on body composition. Sure enough, researchers found that lots of physical activity (based on frequency, duration, and perceived physical exertion of more than 60 exercises) was an effective way to mitigate and perhaps even offset air pollution exposure.

Wang notes, however, that since this project only included middle-aged women, its findings should not be generalized to either men or women of different age groups.

The study is published in the journal Diabetes Care.

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