There is good news for some men over 50: being just a little overweight is not unhealthy.

But as the scales tip higher - say above 168 pounds (76 kg) for a 5’ 7” (1.70 meter) male - the risk of premature death increases dramatically, according to a study of more than half a million members of the AARP, an advocacy group for U.S. retirees.

Yet for women, there’s no late-in-life leeway - being overweight to any degree significantly increases their health risks.

“People who are overweight have a modestly increased risk of premature death,” Michael Leitzmann, of the National Cancer Institute and a co-author of the study released this week in The New England Journal of Medicine, told Reuters.

“For women, the risk begins immediately when you hit the overweight range, whereas for men you need to travel somewhat higher into the overweight range to hit that increase,” said Leitzmann.

The research aims to resolve lingering controversy over whether being overweight carries the same health risks as obesity.

Being overweight is defined as having a body-mass index of between 25 and 30. The BMI is based on weight and height. A BMI calculator with both English and metric units is available online at http://www.nhlbisupport.com/bmi.

The 1999 Cancer Prevention Study II, funded by the American Cancer Society, found that the death rate rose for those who were both underweight and overweight.

But the federally funded National Health and Nutrition Examination Survey did not find in a 2005 study that being a little overweight or underweight increased health risks.

The problem is smoking, which tends to keep people leaner even as smoking-related illnesses are more likely to kill them. This distorts the death rates when researchers try to assess the effects of those extra pounds.

WEIGHT RISKS

To exclude the effects of smoking, the AARP study looked at the death rates of 186,000 men and women who never smoked and found that that demonstrated the dangers of being overweight.

For a 5’ 7” (1.70 meter) male, the highest “normal” weight is now considered 159 pounds (72 kg). But health risks did not emerge until the scale tipped 168 pounds (76 kg) for men who had never smoked, according to the Leitzmann study.

Above that, however, the risk of premature death started to increase, sometimes dramatically.

The death rate for men of the same height who weighed 169 pounds (77 kg) was 9 percent higher than for those in a group weighing slightly less. It was 20 percent higher at 180 pounds (82 kg), nearly 40 percent higher at 200 pounds (91 kg), 91 percent higher at 225 pounds (102 kg), and more than 2.5 times higher for men above 255 pounds (116 kg).

The study was conducted by the National Institutes of Health. A second New England Journal of Medicine study of the weight and mortality rates of more than 1.2 million South Korean adults also found higher risks with extra pounds.

“This finding is a sobering reminder that because obesity is now a worldwide problem, the phenomenon of ‘global fattening’ will contribute to a pandemic of chronic diseases for many years to come,” said Timothy Byers of the University of Colorado School of Medicine, in a journal commentary.