Fitness & fatness: Laurie Taylor asks if they are two sides of the same coin. He's joined by Jürgen Martschukat, Professor of North American History at the University of Erfurt and author of a new book which looks at the history of self-optimisation from the Enlightenment to the present. What’s the relationship between neoliberalism and phenomena like Viagra & aerobics ? How did the body come to symbolise success and achievement? Also, Sarah Trainer, medical anthropologist at Seattle University, discusses her study on extreme weight loss, via bariatric surgery. Her in depth interviews with patients reveal, in painstaking detail, how the journey to drastic weight - often half a person's body weight - can be at once painful and liberating, revealing which bodies are treated as though they don't belong in modern societies. Producer: Jayne Egerton