In the second of three programmes, the volunteers leave the lab and take their diets home, where they face the challenge of sticking to their weight-loss plans while dealing with all the stresses and temptations of their real lives. Geneticist Giles Yeo uses eye-tracking technology to investigate how the Constant Cravers are affected by their 'hungry genes', while Tanya Byron visits Cambridge University to discover what happens in the brains of Emotional Eaters to compel them to comfort eat. The Feasters are brought together for a test by Fiona Gribble, who wants to find out why soup is such a great dieting tool.