Chinese men and women on the verge of what is considered overweight among Causcasians actually showed the lowest risk of death when compared to their own cultural counterparts, said a study on Monday.
The 10-year study followed nearly 59,000 men and nearly 66,000 women in Taiwan and examined the links between mortality and body mass index, a mathematical formula that uses height and weight.
Most people fall somewhere on the spectrum of 18 to 35. The US Centers for Disease Control considers a BMI of 25 to 29 overweight and 30 or higher obese, and says those groups face a higher risk of diseases and health problems.
In the Taiwan study, "the lowest risk of death was observed among men and women who had a BMI of 24.0 to 25.9," said the study published in the Canadian Medical Journal.
"In this population-based prospective study, we found a U-shaped association between BMI and all-cause mortality among adult Chinese people in Taiwan," the study said.
"The risk of death was higher among people people with BMIs in the lower and upper categories than those with BMIs in the middle category."
Similar associations were seen when the researchers analyzed data by age, smoking and pre-existing disease, the study said.
Given those findings, the authors said the research does not support an effort by the World Health Organization to lower the values for defining "overweight" people in Asian populations to 23.0-24.9.
The average man in the study with a BMI of 24-25.9 was 168 centimeters tall (five feet, five inches) and 70 kilograms (154 pounds).
The average woman with a BMI of 24-25.9 was 153 centimeters tall (five feet) and 64 kilograms (141 pounds).
In a commentary on the study published in the journal, Shankuan Zhu of Zhejiang University said the findings "are important because they seem to challenge the current definitions of overweight and obesity and are inconsistent with the pattern found in white populations and for the relation between BMI and chronic diseases, in particular cardiovascular diseases."
BMI is not always an accurate measure of body fat, which is more closely tested by "measurements of skinfold thickness and waist circumference, calculation of waist-to-hip circumference ratios," the CDC said.