According to latest studies, it has come to light that people who are underweight or slightly below normal run the risk of death after surgery more than those who are overweight. Although scientists did not speculate on what causes heavier people to be safer, it has been conclusively proved that lighter people run higher risk.Study focused on establishing a link between body mass index of a person and the risk of death after surgery, not only immediately or during surgery but within thirty days. Body mass index is a factor that is based on height and weight of a person. If the index is between 18.5 and 24.9, it is normal. Overweight is between 25 and 29.9 and beyond 30, it is obese. When BMI is below 18.5, the person is said to be underweight. The study has been carried out by Dr. Florence E. Turrentine from the department of surgery in University of Virginia.

Data for the study was provided by the American College of Surgeons National Surgical Quality Improvement Program. In all, 183 hospitals and medical facilities where operations were conducted were considered for the study. The total number of patients considered was 189,533. Data was collected for the years 2005 and 2006. Of the total data collected, it was found that 1.7% of them died after the surgery within a span of thirty days. Conclusions were drawn based on the relation between BMI, type of surgery, physical health of patients and other influencing factors.

The researchers found that people who had a BMI of less than 23.1 faced a higher risk of death after surgery. The odds against these people were 40% more than with people of a higher body mass index. Dr. Turrentine said that after balancing all other influencing factors that lead to death after surgery and only concentrating on the BMI, it has been found that BMI does have an impact on survival rates. The study was conducted on different kinds of surgeries and it was found that death rate varied with the body mass index of the patient. This stands true for death due to surgery until a month.

Being underweight could lead to an increased risk of death because of the weakness in the body, lower immunity and decreased resistance. In comparison, heavier people are not weak and have the resistance to bear with the strain that the body undergoes during surgery. However, being obese is not good for general health. Being in the mid range of normal is the healthiest BMI.