Julian Pettifertravels to Taipei to explore the growing problem of child obesity in Taiwan. With a fifth of school-age boys now overweight, schools are picking out heavier children and giving them three weekly sessions of compulsory exercise. Pettifer investigates the causes of the problem and asks how far doctors can hope for success. Producer Polly Hope. Repeated Monday 8.30pm WEBSITE: www.bbc.co.uk/continents