For years we've been hearing about the health risks associated with obesity. As your body mass index rises, so does your risk for coronary heart disease. Obesity also can lead to stroke, diabetes and high blood pressure.

But now a new study is sending a message that at first may seem a bit topsy-turvy: that middle-aged people with a body mass index (BMI) in the category of slightly overweight have higher chances of living longer than any other weight category.

BMI is a number derived from a person's weight and height that's used to calculate body fatness.

The nationwide study of nearly 10,000 people found that those who were slightly overweight in their 50s but kept their weight relatively stable were the most likely to survive over the next 16 years. They had better survival rates than even normal-weight people whose weight increased slightly, but stayed within the normal range. On the other hand, those who started out as very obese in their 50s and whose weight continued to increase were the most likely to die during that period.

Overall, the results suggest that about 7.2 percent of deaths after the age of 51 are due to weight gain among obese people, at least among the generation in this study, said Hui Zheng, lead author of the study and assistant professor of sociology at The Ohio State University, in a press release.

"You can learn more about older people's mortality risk by looking at how their weight is changing than you can by just looking at how much they weigh at any one time," Zheng added.

Zheng emphasized that the study's results applied only to those over 50. Previous research, he noted, suggests that being overweight may not be helpful for younger people.

"Our other research suggests that the negative effect of obesity on health is greater for young people than it is for older people, so young people especially shouldn't think that being overweight is harmless," he said.

So who is being slightly overweight beneficial for older people?

"It is probably because the older population is more likely to get illnesses and disease, especially cancer, that cause dangerous weight loss," Zheng said. "In that case, a small amount of extra weight may provide protection against nutritional and energy deficiencies, metabolic stresses, the development of wasting and frailty, and loss of muscle and bone density caused by chronic diseases."

Younger people are less likely to get many of the diseases that afflict older adults, which is one reason extra weight is not good for them, he said.

But Zheng said the main takeaway for everyone, including older adults, is that packing on the pounds, especially if you're obese, can be hazardous to your health.

"Continuing to put on weight can lower your life expectancy," he said.

This new study was published online this month in the American Journal of Epidemiology.

In an analysis of 97 studies released earlier this summer, researchers from the Centers for Disease Control and Prevention (CDC) found that being overweight actually lowered a person's risk of dying from any cause by 6 percent.

What do you think? Let us know in the comments section.


Earlier on HuffPost50:

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  • 1. Make Bad Dietary Choices

    Over the years, there's been a lot of debate related to diet and longevity. But most experts agree that a <a href="http://www.huffingtonpost.com/jay-williams-phd/best-diets_b_2268460.html" target="_blank">diet low in sugar and refined carbohydrates is best</a>. And some studies show that eating a traditional <a href="http://journals.cambridge.org/download.php?file=%2FBJN%2FBJN84_S2%2FS0007114500002701a.pdf&code=a4a2995aa69a094808c095f29250a990" target="_blank">Mediterranean diet</a> can add years to your life.

  • 2. Never Check Your Cholesterol

    Just like high blood pressure, <a href="http://www.webmd.com/heart-disease/guide/heart-disease-lower-cholesterol-risk" target="_blank">high cholesterol can also increase your risk of heart disease</a> and stroke. Therefore it's a good idea to have your cholesterol checked to see whether you need to undergo certain lifestyle changes or even possibly take some kind of cholesterol-lowering medication. For more information about cholesterol and saturated fats, go <a href="http://www.hsph.harvard.edu/nutritionsource/fats-full-story/" target="_blank">here.</a> Eating certain foods, such as beans, which are rich in fiber and antioxidants, can help lower cholesterol.

  • 3. Mix Alcohol And Prescription Or Illicit Drugs

    <a href="http://www.huffingtonpost.com/ann-brenoff/whitney-houston-prescription-drugs_b_1280439.html" target="_hplink">Even drinking wine with dinner and then taking prescription sleep aides can be a lethal combination</a>. A U.S. Department of Health and Human Services study found 5.8 percent of people age 50 to 59 used illicit drugs in 2010, up from 2.7 percent in 2002.

  • 4. Never Check For Diabetes

    The number of Americans with <a href="http://www.diabetes.org/" target="_hplink">Type 2 diabetes</a> is expected to rise from 30 million today to 46 million by 2030, when one of every four boomers -- 14 million -- will be living with this chronic disease, according to the National Center for Chronic Disease Prevention and Health Promotion. <br /> <br />Untreated diabetes can lead to blindness, amputations and clogged arteries that can cause heart attacks and strokes. The test to determine whether you are diabetic is a simple blood test; you should remind your doctor to include it in your annual physical.

  • 5. Pack On The Pounds

    More than one out of every three boomers -- more than 21 million -- will be considered obese by 2030. Already, we are the demographic with the highest and fastest-growing rate of obesity. As we age, our metabolism slows down and we burn fewer calories -- if we don't alter our eating and exercise patterns, weight gain is inevitable. Obesity can lead to high blood pressure, heart disease, and a host of other life-threatening ailments. <a href="http://www.huffingtonpost.com/ann-brenoff/the-dieting-10-percent-club-losing-weight-after-50_b_1440729.html" target="_hplink">Losing just 10 percent of your body weight</a> has health benefits, so consider that as a goal.

  • 6. Ignore The Signs Of A Heart Attack

    No chest pain doesn't mean no heart attack. <a href="http://www.webmd.com/heart-disease/features/her-guide-to-a-heart-attack" target="_hplink">Women having heart attacks</a> frequently report experiencing a feeling of indigestion and extreme fatigue, while some men say they feel a fullness or a squeezing pain in the center of the chest, which may spread to the neck, shoulder or jaw. When a diabetic has a heart attack, the pain is often displaced to other areas such as the lower back.

  • 7. Get Little Sleep

    Try as you might, you just can't stay asleep, right? You pass out before "60 Minutes" is over, but then wake up around midnight and count sheep until the alarm goes off. If that sounds like you, you aren't alone. The U.S. Centers for Disease Control and Prevention says that <a href="http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5842a2.htm" target="_hplink">boomers report not getting enough sleep between one and 13 nights each month</a>. Is it life-threatening? In itself, no. But as soon as you slip behind the wheel bleary-eyed, you are putting yourself and others at risk. Your reflexes are slower, you pay less attention and you could become one of the more than 100,000 Americans who fall asleep at the wheel and crash each year. And the <a href="http://drowsydriving.org/about/facts-and-stats/" target="_hplink">National Highway Traffic Safety Administration</a> says that's a conservative estimate, by the way. Driver fatigue results in an estimated 1,550 deaths, 71,000 injuries and $12.5 billion in monetary losses.

  • 8. Avoid Exercise

    AARP says the minimum you need to stay healthy are muscle-strengthening exercises twice a week, plus 2.5 hours a week of moderate activity like walking or 75 minutes a week of a more intense activity like jogging. Exercise is also good for your memory: Just one year of <a href="http://www.aarp.org/health/brain-health/info-02-2011/keep_your_memory_strong_by_walking.html" target="_hplink">walking three times a week can increase the size of the hippocampus</a>, the part of the brain that's key to memory.

  • 9. Carry The World's Burdens On Your Shoulders

    We're talking about stress with a capital S. Boomers are the sandwich generation, caught in the middle of caring for our parents and our children. We were deeply affected by the recession and <a href="http://www.huffingtonpost.com/ann-brenoff/midlife-crisis-depression-is-ok-the-new-good_b_1470958.html" target="_hplink">boomers have the highest rates of depression</a> by age demographic. Unless we unload, we are going to implode.

  • 10. Carry A Beer Belly And A Caboose

    It isn't just our extra weight; it's where we carry it. An excess of visceral fat causes our abdomens to protrude excessively. We call it a "pot belly" or "beer belly" or if the visceral fat is on our hips and buttocks, we say we are "apple shaped." Cute names aside, scientists now say that body fat, instead of body weight, is the key to evaluating obesity. And guess what? It's all bad.

  • 11. Continue To Smoke

    <a href="http://www.gallup.com/poll/128183/smoking-age-baby-boomer-bulge.aspx" target="_hplink">Gallup found that baby boomers between the ages of 44 and 54 reported higher levels of smoking</a> than those immediately younger or those who are older. Hard to imagine that they haven't gotten the word yet about the risks cigarettes carry.