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When it comes to losing weight and getting healthy, procrastination kills

Here on the hopeful threshold of the new year, the last thing anyone wants to hear is that losing that excess weight we've been lugging around doesn't matter.

So when a new study comes along that seems to tell us just that, we could let it dash our resolutions and have another cookie. Or, we could actually read the research and find out that what it's telling us is that, when it comes to losing excess weight and getting healthy, procrastination kills.

So put down the cookie and fetch your sneakers.

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New research published this week in the Proceedings of the National Academy of Sciences suggests that, too often, many of us put off weight loss until our excess weight has already eroded our health--setting in motion heart disease, Type 2 diabetes or even cancer, all conditions linked to obesity. When our bodies are already under attack by disease, or hounded by its imminent prospect, we tend to lose weight, sometimes without even trying.

Maybe we even lose enough to exit the rolls of the obese -- an achievement we should fear, not welcome, for it is often a harbinger of imminent death.

In fact, dropping that much weight intentionally is depressingly rare: Research has found that fewer than 5% of those who lose a substantial amount of weight maintain that weight loss for five years or more. Once obesity has been established, most who intentionally lose enough to enter the "normal healthy weight" category gain back their lost weight -- often adding more -- studies find.

The latest study looks at weight and risk of death. Its authors set out to replicate an influential 2013 finding that spurred a hypothesis widely known as the "obesity paradox." Writing in the Journal of the American Medical Assn., epidemiologists from the Centers for Disease Control and Prevention reported that being overweight (with a body mass index from 25 to 29.9) seemed to confer some protection against premature death, and that the mildly obese (those with a BMI from 30 to 34.9) were at no higher risk of premature death that those of normal weight.

What the authors of the current study found instead is that, to accurately gauge risk of premature death in a large population of people, it's more revealing to ask people what their highest lifetime weight has been rather than to ask--as most researchers have done--what their weight is now.

In epidemiological surveys of Americans, people who were once obese but are no longer are generally counted as people of "normal healthy weight." But the current study's lead author, Boston University demographer Andrew Stokes, says such people are far more likely to have lost that weight unintentionally, due to illness, than to be among the few who have intentionally lost lots of weight and kept it off through sheer tenacity.

When Stokes and University of Pennsylvania's Samuel H. Preston looked at people's death rates as a function of their highest-ever weight (excluding pregnancy weight for women), they discovered that those who were once obese but are no longer were far more likely to die prematurely than were people who used to be obese and remained so.

Two factors suggest that most of those no-longer-obese people were not healthy, said Stokes: First, there's the age of the study participants -- 50 to 75 -- a period when disease is most likely to take hold. Second is the simple fact that so few Americans who are healthy appear able to lose weight and keep it off. The biology of a healthy person works hard to regain lost weight.

On the face of it, the findings may suggest that losing weight doesn't help an obese person to improve his or her odds of living a long life.

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That's wrong, says Stokes: "We would never claim that healthy weight loss is a bad idea," he said. When a person purposely loses weight, his or her health status clearly improves, he added.

Instead, Stokes said, his findings make an important methodological point: that researchers who fail to ask people what their highest weight was will miss a whole class of people who are probably in the process of dying prematurely of obesity-related diseases. These people may have a "normal healthy weight," and they are counted by researchers as normal and healthy. But they are probably anything but, said Stokes.

As a result of such methodological oversights, the researchers wrote, "the burden of overweight and obesity on mortality is likely substantially larger than commonly appreciated." Despite stabilizing or even declining rates of obesity, they added, "this may have serious implications for the future of life expectancy in the United States." A pattern of decades in which each birth cohort was heavier than the last could "exert upward pressure on U.S mortality levels for many years to come."

To those who would conclude that being--and staying--overweight or obese is not dangerous, Stokes says, not so fast. In his study, people who have ever been overweight or obese are at decidedly higher risk of premature death than those who have never been either.

"These findings emphasize the importance of obesity prevention," said Stokes.

If it's too late for prevention, it's not too late to lose some weight, the new research suggests. Just do it -- purposely -- before it is too late, when that extra weight may just come off without a fight.

Follow me on Twitter @LATMelissaHealy and "like" Los Angeles Times Science & Health on Facebook.

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