Heavy and grey is the head that wears the crown - a lesson that President Obama and many of his predecessors have learned the hard way. When Mr Obama takes the oath of office next Monday marking the beginning of his second term, it will not be the same smooth-cheeked, black-haired man who first joined the exclusive club of leaders of the free world in 2008. Comparing pictures of the 51-year-old commander-in-chief from four years to those taken more recently reveals a startling yet obvious truth: standing at the helm of the U.S. government takes a heavy physical toll. Read...