America is losing the war against childhood obesity. This seemingly unstoppable epidemic is the single biggest health risk to our youth, and in most cases, it's completely avoidable.  Today's guest is the world-renowned Dr. David Ludwig, a man who has dedicated his life to saving our children from this scourge with his cutting-edge research at Harvard. In this episode, Dr. Ludwig reveals the science behind why our children are most vulnerable to childhood obesity, and how a change of diet can save their lives.