(CBS) Being thin might not be "in" when it comes to surgery.
A new study suggests skinny people are much more likely to die after surgery than their overweight counterparts.
For the study, published in the Nov. 22 issue of the Archives of Surgery, researchers examined the relationship between body mass index (BMI) and risk for death among 190,000 surgical patients who underwent a procedure between 2005 and 2006.
The researchers found 3,200 patients died within 30 days of surgery. After taking a closer look at patients' BMIs, the researchers found nearly 3 percent of deaths were among underweight patients with a BMI less than 23.1, compared with 1 percent of deaths among obese patients with a BMI of 35.3 or higher. Patients with a BMI less than 23.1 were up to 40 percent more likely to die than overweight patients with a BMI between 26.3 and 29.6.
"These results indicate that BMI is a significant predictor of mortality within 30 days of surgery," the authors said in a written statement.
What's so bad about being skinny for surgery? The researchers themselves aren't sure, but Dr. Nestor de la Cruz-Munoz, chief of bariatric surgery at the University of Miami Miller School of Medicine, told HealthDay that the findings make sense.
"A lot of these patients are malnourished - maybe cancer patients, patients undergoing treatment for other medical problems," de la Cruz Munoz said. "A lot of time these patients don't have the defenses to do well with a major surgery. These patients are not your skinny young girl, but more like a frail 80-year-old woman."
According to the National Institutes of Health, people with a BMI under 18.5 are considered underweight, those with a BMI 18.5-24.9 are normal weight, 25-29.9 are overweight, and people with a BMI of 30 or greater are considered obese.
The National Heart Lung and Blood Institute has more information on maintaining a healthy body weight