This week at TEDMED, we’ll be focusing on a Great Challenge with perhaps the biggest impact on future health: reducing childhood obesity. Some 17 percent – 12.5 million – of kids in the U.S. are obese. How did we get here, and what can we do about it? Watch Judith Salerno and John Hoffman talk about “The Weight of the Nation” at TEDMED 2012 – and join our live online event this Thursday at 1 pm ET. Moderating the discussion is Sally Squires, former Washington Post nutrition columnist and Director of Health and Wellness for Powell Tate. Visit TEDMED’s Google Plus page for details. Ask questions of our group of health leaders on the topic – they may answer them on air.