People who are underweight have almost double the risk of dying than those who are obese.
Study leader Dr. Joel Ray, a physician-researcher at St. Michael’s Hospital and the hospital’s Li Ka Shing Knowledge Institute in Toronto, said the connection between being underweight and the higher risk of dying was true for both adults and fetuses.
Ray and colleagues conducted a meta-analysis including 51 studies on the links between body mass index and deaths from any cause, plus data on newborn weight and stillbirths in Ontario.
The analysis, published in the Journal of Epidemiology and Public Health, found underweight adults with a BMI 18.5 or less have a 1.8 times higher risk of dying than those with a normal BMI of 18.5 to 24.9. Further, the risk of dying was 1.2 times higher for people who are considered obese, with a body mass index of 30 to 34.9, and 1.3 times higher for those who are severely obese -- a BMI of 35 or higher.