We wuz wrong! -- again: "Doctors have cast doubt on the standard way of measuring whether people are obese or overweight. New research suggests shortcomings in the system of Body Mass Index (BMI) in identifying whether someone is at risk of dying prematurely. Studies show that heart patients identified as 'overweight' by BMI actually survived longer than those judged to have a 'normal' weight. This is because the system fails to identify if a person's excess weight is muscle rather than fat. If someone is heavy because of muscle, they are less likely to die younger - and should not be classed as overweight - compared to someone whose excess weight is mostly fat. According to the BMI, which has formed the basis of defining healthy and abnormal weight for more than 100 years, more than half the UK population is overweight and a further 20 per cent obese".