Dr Rexford Ahima, a medical professor at the University of Pennsylvania, in Philadelphia, and co-author of the editorial said that most studies depend on BMI, asserting that it's not a very accurate measure.
According to many studies, people having BMIs above 30 are at an increased risk of dying from heart disease, diabetes, cancer and other diseases.
However, recent studies have shown that in some cases, a high BMI may protect a person from dying of heart failure, kidney failure and other chronic diseases.
Someone having a chronic illness, having more fat may provide additional energy reserves and is some cases, a low BMI could be a result of a person having an illness.
Ahima said that BMI does not take into account fat and doesn't indicate the fat distribution in the body.
The study has been published in the journal Science.