Canned food is a source of BPA exposure, but researchers aren't sure whether it causes childhood obesity. Above, the soup isle at a grocery store in Washington, D.C. Maggie Starbard/NPR hide caption

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Childhood obesity is on the rise in many countries and overuse of antibiotics is now on the radar as a possible factor in the epidemic. Here 18-month-old twins are weighed in a nutritionist's office in Colombia. Raul Arboleda/AFP/Getty Images hide caption

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Karlton Hill, 15, was diagnosed with diabetes when he was 12. He works hard to manage the disease: He jogs and does pushups every day; he takes metformin is very careful about what he eats. Leslie Capo/LSU Health Sciences Center hide caption

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Moms and their kids protest a proposed ban on homemade food at bake sales in New York City schools at a rally near City Hall in 2010. One sign read, "I wanna get obese on my terms. No junk food." edenpictures/Flickr hide caption

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People stroll down a street in Montpelier, Vt., last summer. In 1995, 13.4 percent of Vermonters were considered obese. The figure climbed to 23.5 percent in 2011. The latest national data suggest the obesity epidemic has plateaued, however. Toby Talbot/AP hide caption

itoggle caption Toby Talbot/AP

Alexandria Johnson got involved with the Anderson Monarchs soccer team when her mother was looking for an affordable way to keep her active. Todd Vachon/WHYY hide caption

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