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Have you heard of the “obesity paradox”? It’s a well-known belief that overweight or obese people with heart disease live longer than people of normal weight with similar conditions. That may sound unlikely, but some evidence appearing to confirm it has accumulated over the years.

Now, though, a study reviewing previous research declares the obesity paradox is a myth.

Probing the paradox

“I get a lot of patients who ask, ‘Why do I need to lose weight if research says I’m going to live longer?’” said Sadiya Khan, MD, an assistant professor of medicine at Northwestern University and senior author of the study, in a news release.

Researchers at Northwestern took a closer look at the obesity paradox. They analyzed 50 years of health records on more than 190,000 people who had taken part in 10 major studies. None of the participants had been diagnosed with heart disease at the beginning of their study. Each individual was followed for at least 10 years. Clear patterns emerged in who developed heart problems and who didn’t.

“Our data show you will live longer and healthier at a normal weight,” said Khan.

Measuring heart risks

Compared to people of normal weight, the lifetime risk of stroke, heart failure, heart attack, or cardiovascular death was 21 percent higher in overweight middle-aged men and 32 percent higher in overweight middle-aged women.

Obesity raised that risk even more: 67 percent greater than normal for men and 85 percent for women. For the heaviest participants, the risk was still higher.

Losing longevity

Obesity in middle-aged people was also associated with a shorter lifespan, not a longer one.

Normal-weight men lived nearly two years longer than obese men and six years longer than those who were morbidly obese. Being overweight (but not heavy enough to be obese) didn’t significantly affect longevity in men.

Women of normal weight lived almost one and a half years longer than overweight women, 3.4 years longer than obese women, and six years longer than morbidly obese women.

How a myth was born

With such strong evidence to the contrary, how did the obesity paradox gain credibility in the first place? One explanation is that results of studies seeming to confirm the paradox were misunderstood.

Some research looked at how long people lived after they were diagnosed with heart disease. Heavier people did indeed live more years after diagnosis than people of normal weight. But that’s misleading because heavier people were typically diagnosed with heart trouble earlier in life. They lived more of their lives with heart disease, but still died at a younger age.

Improving your odds

This study might not be the last word on the obesity paradox, but it strongly suggests that maintaining a healthy weight may reduce your heart risk. That could increase your chances of living a longer life—and feeling your best so you can enjoy it.

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