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From VOA Learning English, this is the Health Report in Special English.
New research shows that overweight or even mildly obese people have a lower risk of early death than people considered to be normal weight.
Researchers examined the results of 97 studies. Most of the studies were less than 10 years old. They included almost three million adults from around the world, including the United States, Canada, China, Taiwan, Brazil, India and Mexico.
The researchers work at the National Center for Health Statistics, part of the United States Centers for Disease Control and Prevention.
They found that people who are considered overweight or slightly obese were five to six percent less likely to die from all causes than people of normal weight. People with higher obesity ratings, however, had almost a 30 percent greater risk of death compared to normal-weight individuals.
Katherine Flegal was the lead author of the study. She says she was not surprised that overweight people would not have a higher risk of death.
"Because we'd actually already read a lot of this literature and realized it was likely that [mortality rates for] overweight would be at least not higher than normal weight. I guess I was a little bit surprised that it was definitely lower. And I was also surprised that the lower rates of obesity also didn't seem to differ from normal weight."
But she says the difference in death rates appears to be small between normal-weight people and those who are overweight or mildly obese.
The study has raised new questions about "body mass index," or BMI. This is a measurement of body fat as a ratio of height to weight. BMI guidelines were used as a basis for the study. In recent years, many public health experts have promoted body mass index as a way to predict the risk of health problems. But a person's BMI can be misleading in some cases.
Steven Heymsfield is the executive director of the Pennington Biomedical Research Center in Baton Rouge, Louisiana. He says people can be physically fit and in good health, but might weigh more because they are more muscular.
"It's very common in the military, for example, where you have young men and women who are very physically fit -- their BMI can be a little higher. And so the military knows that, and they check people with body fat measurement if they exceed the BMI guideline."
Still, Dr. Heymsfield says people should not think gaining extra weight is OK just because of the new findings. He says being at a healthy weight lowers the risk for heart disease and diabetes. He and a colleague wrote an editorial that appeared along with the study in the Journal of the American Medical Association.
n. 测量，衡量，尺寸，大小
