Chinese people with a body mass index (BMI) of 24-25.9 had the lowest risk of death, according to a study published in CMAJ (Canadian Medical Association Journal).
Obesity has increased significantly across the globe and the World Health Organization (WHO) estimates that about 2.3 billion adults will be overweight and more than 700 million will be obese by 2015. Overweight and obesity are associated with increased risks of heart disease, diabetes, cancer and other chronic diseases.
As white populations have served as the benchmark for definitions of overweight and obesity, the WHO has suggested a lower cut-off for overweight and obesity in Chinese populations.
This study, by researchers from Taiwan and the US, looked at 58 738 Chinese men and 65 718 women in Taiwan aged 20 or older to find the association between BMI and risk of death from any cause. They found that people with a BMI of less than 24 with a chronic disease were at higher risk than those without a chronic disease. Smokers with lower BMIs had a higher risk of death. People with a chronic disease and a higher BMI (above 30) had a lower risk of death.
The lowest risk of death was among men and women with a BMI of 24-25.9, compared with white populations in which the lowest risk has been reported among people with a BMI of 22.5-24.9.
"The risk of death was higher among people with BMIs in the lower and upper categories than among those with BMIs in the middle category," writes Dr. Wen-Yuan Lin, China Medical University, Taichung, Taiwan, with coauthors.
"The findings from our primary analysis and sensitivity analyses are consistent with the results of [other] studies and do not support the use of a lower BMI cutoff value for overweight and obesity in the adult Chinese population," state the authors.
In a related commentary, Dr. Shankuan Zhu, Zhejiang University, Hangzhou, China, and coauthors write "the findings in the study by Lin and colleagues 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."