Being Underweight Deadlier than Being Obese

New research suggests that being very thin may be even deadlier than being very fat. Dr Joel Ray, a physician-researcher at St Michael's Hospital in Toronto (Canada), and colleagues conducted a meta-analysis of 51 studies evaluating the links between body mass index (BMI) and death from any cause. Results showed that adults who are underweight (a BMI of 18.5 or less) have a 1.8-times higher risk of dying compared to adults with a "normal" BMI of 18.5 to 24.9. In comparison, people who are obese (BMI of 30-34.9) were found to have a 1.2-times higher risk of dying, while people who are severely obese (a BMI of 35 or higher) were found to have a 1.3-times higher risk of dying. The relationship between being underweight and the higher risk of dying remained true even when factors such as smoking, alcohol use or lung disease were taken into account, and when adults with a chronic or terminal illness were excluded. "BMI reflects not only body fat, but also muscle mass. If we want to continue to use BMI in health care and public health initiatives, we must realize that a robust and healthy individual is someone who has a reasonable amount of body fat and also sufficient bone and muscle," said Dr Ray. "If our focus is more on the ills of excess body fat, then we need to replace BMI with a proper measure, like waist circumference."