Michael Mosley has set himself a truly ambitious goal: he wants to live longer, stay younger and lose weight. But he wants to make as few changes to his life as possible along the way. And he thinks he's found the answer -- the ancient idea of fasting. Could the powerful new science behind this idea lead to a longer, healthier life? Mosley thinks he's found a way of fasting that still allows him to enjoy his food. It sounds too good to be true. So he decides to take a road trip across the U.S. to investigate how a little hunger can make you younger -- and of course -- to try out some of this new science for himself.