Michael Mosley has set himself a truly ambitious goal: he wants to live longer, stay younger and lose weight. 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 US to investigate how a little hunger can make you younger, and of course, to try out some of this new science for himself.