Being svelte may have its advantages when squeezing into skinny jeans — but it may also carry significant risks should you need to undergo surgery for any reason. This was the startling conclusion of a new study just published in Archives of Surgery, which found a 40% higher likelihood of dying in the 30 days following an operation for those in the lowest quintile of body weight.

The study authors used a national surgical database drawing from 183 hospitals to see the impact of body mass index (BMI) on mortality risk in the month window after surgery. Of the nearly 190,000 patients included in the analysis, those with a BMI under 23 (the equivalent of a 5 foot, 9 inch person with body weight of 155 lbs) had 40% higher risk of post op death, four weeks out. While the authors caution that the lower weight patients could have been sicker to begin with, it’s also true that being underweight carries its own set of health risks — such as compromised immunity — which may complicate recovery.

While a paucity of pounds may pose post-surgical problems, only 2% of the population is underweight. The two-thirds of the population that is overweight or even obese face their own set of surgical challenges. One analysis by the Washington University School of Medicine, Missouri found that those obese at the time of surgery were 2.2 times more likely to suffer a hospital infection. Not only does obesity make it more likely you’ll end up in the hospital in the first place, the extra pounds could hamper the accuracy of important diagnostic scans. Regardless of weight, eating a healthy diet with plenty of fruit and vegetables will help support a healthy immune function and a timely recovery.

Published January 1, 2012