The truth about exercise.

Michael Mosley looks at the latest research into the health benefits of exercise. He begins by attempting to race Olympic runner, Will Sharman, and works out how many calories he loses during a jog. Jason Gill measures how much fat Mosley has in his blood after a particularly fatty meal, then after the same meal when enzyme, lipoprotein lipase, has been triggered by a strenuous walk. Mosley learns that exercise routines should ideally be tailored to the individual and he embarks on a new study with Jamie Timmons, which measures how fit he is and tailors a short sharp exercise routine for Mosley. Obesity expert, James Levine, explains NEAT (non-exercise activity thermogenics), which measures how many calories we burn in everyday activities. Emma Ross describes her research into what it is that makes us tired during exercise. Mosley concludes that different modes of exercise suit different people but for those of us leading a sedentary life, the chair is the killer.