Professor Tim Spector, a leading expert on nutrition and gut health, takes Michael Mosley through his top food and nutrition tips, sharing stories from his life and research along the way. Joined by an audience at the Hay Festival, Michael learns what happened the time Tim convinced his son to eat an ultra-processed food diet for two weeks and the surprising ways your gut influences your immune system. Tim, who is professor in epidemiology at King's College London, shares the shocking moment he realised that even as a doctor, he was on track for major health problems, and how he took control over his diet and his health - and how you can, too. Tim also reveals what cutting edge science shows about how you should be eating to benefit your health and wellbeing.