Obese people are more likely to die earlier, right? Wrong, according to new research our of Denmark. The study was just published in the Journal of the American Medical Association

The research from University of Copenhagen analyzed data on over 100,000 individuals to reveal that in 1976-1978, the risk of premature death from all causes was higher in obese individuals than in normal-weight individuals, but this was no longer the case in 2003-2013.

“The increased risk of all-cause mortality associated with obesity compared to normal weight decreased from 30% 1976-78 to 0% in 2003-13,” says principal investigator Dr. Shoaib Afzal, Herlev Hospital, Copenhagen University Hospital, Denmark.

For years we have looked to the BMI – Body Mass Index – for our cues regarding how much we should weigh, and this new study does not change that, but it does skew the numbers a bit.

“The optimal BMI for the lowest mortality increased from 23.7 in 1976-78, through 24.6 in 1991-94, to 27 in 2003-13, while individuals with a BMI below or above the optimal value had higher mortality,” adds Shoaib Afzal.

The BMI is measured dividing height in centimeters by 100 to obtain height in meters. Calculate BMI by dividing weight in pounds by height in inches squared and multiplying by a conversion factor of 703.

“Compared to the 1970’s, today’s overweight individuals have lower mortality than so-called normal weight individuals. The reason for this change is unknown. However, these results would indicate a need to revise the categories presently used to define overweight, which are based on data from before the 1990’s” says senior author Clinical Professor Børge G. Nordestgaard, University of Copenhagen and Copenhagen University Hospital.

Many try to lose weight to avoid diabetes and cardiovascular disease and hopefully live longer. This is often driven by recommendations from health care authorities and is further supported by the media and not least, by commercials often presenting normal weight or even thin people as ideal humans.

But don't get the impression that it's suddenly okay to chow down on a double cheeseburger and large fries for two meals every day.

"Importantly, our results should not be interpreted as suggesting that now people can eat as much as they like, or that so-called normal weight individuals should eat more to become overweight,” Nordestgaard noted. “That said, maybe overweight people need not be quite as worried about their weight as before."