Another piece of cake, please
So now being overweight is good for you.
It has long been known that mortality follows a J shaped relation to weight. Very thin people are at increased risk for death, as are the obese. In the past some, if not all of the mortality in the thin was thought to be from people losing weight when they are sick. For example, many people with cancer lose a lot of weight, but the cancer causes the weight loss, not the other way around.
In this study, they made sure the "thin" people were persistently thin, presumably removing this bias, and still found increase mortality.
This confirms my overall belief that things like good diet and exercise are more important than weight itself. In addition, classification as thin, normal, overweight, obese, etc is based soley on body mass index, which is a simple mathematical relation of height and weight (kg/m^2). But two people the same height and weight can have vastly different body compositons. Alex Rodriguez makes $10 million dollars a year, but has a BMI of 26, making him overweight.
UPDATE: fixed BMI formula which is kg/m^2