Is air pollution making us fat?

Children who live in smog-filled cities are more drawn to fatty foods as adults

Living in smog-filled cities as children can make us eat fattier foods as adults, a new study finds. Researchers say that high levels of particles from power plants and exhaust systems was linked to an increased risk of eating a high trans-fat diet by 34 percent. They also found that the increased levels made people more likely to eat dinner at fast food restaurants rather than at home.

It's not clear exactly why this is the case, though experts say it may be to do with pollutants disrupting how our body absorbs energy from food, sending blood sugar levels plummeting and hunger rocketing.

The team, from the University of Southern California, says their evidence suggests lowering the levels of air pollution in cities across the US could be one way to curb the obesity epidemic.

For the study, published in the American Journal of Clinical Nutrition, the team looked at 3,100 children.

They had been enrolled in the USC Children's Health Study - which looks at the longterm effects of air pollution on children's respiratory systems - between 1993 and 1994 and were followed for 4-8 years. The children answered yearly questionnaires on their diet including how often they ate certain foods and how often they ate out.

Meanwhile, the researchers measured pollutants, including from power plants and car exhausts, and estimated the concentration for participants' residential addresses. The team adjusted for factors including household income, parents' education levels and fast-food restaurants within a 500-meter radius from a child's home or school. They found that the more exposure a child had to air pollutants, mainly from traffic, the more likely they ate a diet high in trans fat.

The new study adds to a growing body of research about the ill effects of air pollution on human health.