A new study by researchers from the United Kingdom has warned that being overweight or underweight can reduce a person's life expectancy، as the Technical Times said. The biggest of its kind، the new study by the London School of Hygiene and Tropical Medicine has linked a healthy body mass index or BMI to a lower risk of dying from heart conditions، cancer، or other life-threatening illnesses. Meanwhile، having too high or too low BMI is linked to an increased risk of dying from every major cause except transport accidents. The study published in the journal The Lancet on Tuesday، Oct. 30، used anonymous data from the Clinical Practice Research Datalink that included BMI from primary care records. This is also linked to the data collected by the Office of National Statistics mortality database that also lists information on causes of death. The researchers then looked at the association between BMI and various causes of deaths. They adjusted the data based on different other important factors such as sex، age، smoking habits، alcohol consumption، and socioeconomic status. The BMI is based on a person's height and weight. The study revealed that obese men have a life expectancy that is 4.2 years shorter compared to those who are in a healthy weight range. Meanwhile، obese women are facing a life expectancy that is 3.5 years shorter than their peers.