Study Links Being Underweight to Higher Risk of Dying: Study

A new study uncovered a strong association between being underweight and a higher risk of dying in both adults and fetuses.

Researchers at St. Michael's Hospital and the hospital's Li Ka Shing Knowledge Institute revealed that underweight people suffer a high risk of dying, similar to obese people. This link is true for both adults and fetuses.  The association remained high even after considering certain factors like smoking, use of alcohol and lung disease.

The study led by Dr. Joel Ray, a physician-researcher at St. Michael's Hospital was based on the results of an analysis of 51 studies that looked at the relation between BMI and mortality from any cause. Researchers also considered data that focused on weight of newborns and stillbirth in Ontario.

"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," Dr. Ray said in a news statement. "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."

The researchers noticed that adults who were underweight (having BMI below than 18.5 or less) were at a 1.8 times higher risk of dying when compared to those with a normal BMI of 18.5-24.9.

The risk of dying was 1.2 times higher in those who were obese (BMI of 30-34.9). Severely obese (BMI more than 35 or higher) individuals were at a 1.3 times higher risk of dying.

Researchers want studies to follow the subjects for five years or more to eliminate those who were underweight because of cancer or some other chronic disease. The common causes of being underweight are malnourishment, high addition to alcohol, smoking, low-income status, mental health or lack of self care.

"We have obligation to ensure that we avoid creating an epidemic of underweight adults and fetuses who are otherwise at the correct weight. We are, therefore, obliged to use the right measurement tool," Dr. Ray said.

The study was documented in the Journal of Epidemiology and Public Health.