From VOA Learning English, this is the Health Report in Special English.
New research shows that overweight or even slightly 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 3 million adults from around the world, including the United States, Canada, China, Taiwan, Brazil, India and Mexico.
The researcher was carried out at the Centers for Disease Control and Prevention in the United States.
The study 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.
But, people with higher obesity ratings had almost a 30 percent greater risk of death compared to normal-weight individuals.
Katherine Flegal led the study.
She says she was not surprised that there was no higher risk for overweight people.
But she had not thought that the risk of death was definitely lower.
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 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.
Steven Heymsfield is head of the Pennington Biomedical Research Center in Louisiana.
He says people can be physically fit and in good health, but might weigh more because they are more muscular.
Still, he cautions that the study's findings should not be an excuse to for people to add a few more pounds.
For VOA Learning English, I'm Laurel Bowman.
(Adapted from a radio program broadcast 16Jan2013)