US Presidents have had their indulgences - Ronald Reagan loved jellybeans and Bill Clinton binged at McDonald's. What's President Barack Obama's weak spot? Pie. Obama's senior adviser, David Axelrod, tells Jay Leno on “The Tonight Show” Friday that the president was forced to “separate” from the White House pastry chef to break his bad eating habits. Axelrod calls it “a big problem.” The chunky-built Axelrod might just be needling his athletic boss, who he said lectures him about diet, exercise and his “beer gut.” It was Axelrod's first appearance on late