In this programme, Michael Mosley finds out why fizzy drinks make you eat more. GP Dr Zoe Williams investigates whether caffeine boosts your physical performance. Geneticist Dr Giles Yeo discovers what men cando about baldness. Surgeon Gabriel Weston looks into the new artificial pancreas that could transform life for diabetics. And Dr Alain Gregoire gives the psychiatrist's guide to obsessive compulsive disorder.