Eat, fast and live longer.

Michael Mosley investigates how fasting can help us live longer. Mosley goes along to the London Marathon and meets a 101 year old Sikh man whose secret of good health is portion control - eating only child portions. Mosley goes to the US where research between 1929-33, the Great Depression, showed that human longevity, despite the many privations, actually increased by six years. It has taken 80 years to get to the bottom of this research. At Washington University, Professor Luigi Fontana leads research into ageing and human physiology. Mosley visits a man, Joe Cordell, known as a 'crony' who eats a giant bowl of fruit for breakfast and then consumes less than 2000 calories per day and has done so for many years. A number of tests indicative of ageing are done such as reaction time and balancing. Physiological tests are more categoric; Mosley has 27% fat whereas Cordell has only 11%. Professor Valter Longo from the University of Southern California has been studying human ageing. A genetically engineered mouse which is very small holds the secret to longer life. There is also a group of people in Ecuador with Laron's syndrome (a form of dwarfism) who have been discovered to be virtually immune to diabetes and cancer. IGF-1, the gene which is responsible controls the potential risk of cardio-vascular disease and cancer. Mosley decides to fast to try to moderate his IGF-1 score; he needs to fast for 3.5 days. Professor Longo reports that fasting has caused a rapid metabolic benefit, cutting his risks of cancer etc considerably. In Chicago Mosley meets Dr Krista A. Varady who has devised a fasting diet which involves severe calorie restriction on alternative days. Tests seem encouraging. Finally in the National Institute of Ageing in Baltimore, Mosley finds out from Professor Mark P. Mattson the impact on ageing on the brain; hunger seems to trigger brain nerve growth. When Mosley returns to London, he decides to follow a 5 week reduced diet; 5 days eating normally, 2 days on a restricted diet. He discovers that his metabolic rate is much improved, his blood glucose, cholesterol as well as his IGF-1 score. He is visibly moved by the results of the blood tests at the end of the trial.