In this week's episode of 'Keeping up with the Purcells,' Andrew and Carrie are faced with their greatest challenge yet - there is no more sugar left in the world and all their recipes need to be rethought in a newer, healthier light.  Enter Truvia.  The seemingly daunting task was far easier than anyone could have thought as mastermind Carrie developed a whole new crop of recipes. And the verdict?  Super sweet.  And by sweet we mean gorgeous!