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Open Access Highly Accessed Research article

Increasing trends in central obesity among Chinese adults with normal body mass index, 1993–2009

Tingting Du1, Xingxing Sun2, Ping Yin3, Rui Huo1, Chaochao Ni1 and Xuefeng Yu1*

  • * Corresponding author: Xuefeng Yu xfyu188@163.com

  • † Equal contributors

Author Affiliations

1 Department of Endocrinology, Tongji Hospital, Tongji Medical College of Huazhong University of Science and Technology, Wuhan, 430030, PR China

2 Department of Anesthesiology, School of Stomatology, Fourth Military Medical University, Xi'an, 710032, PR China

3 Department of Epidemiology and Biostatistics, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, PR China

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BMC Public Health 2013, 13:327  doi:10.1186/1471-2458-13-327

Published: 10 April 2013

Abstract

Background

Central obesity is thought to be more pathogenic than overall obesity and studies have shown that the association between waist circumference (WC) and mortality was strongest in those with a normal body mass index (BMI). The objective of our study was to determine secular trends in the prevalence of central obesity (WC ≥ 90 cm for men and ≥ 80 cm for women) among Chinese adults with normal BMI from 1993 to 2009 and to examine the impact of performance of combined BMI and WC on the prevalence of obesity in Chinese adults.

Methods

We used data from the China Health and Nutrition Survey (CHNS) conducted from 1993 to 2009. From which we included a total of 52023 participants aged ≥ 18 years.

Results

The age-standardized prevalence of central obesity among Chinese adults with BMI < 25 kg/m2 increased from 11.9% in 1993 to 21.1% in 2009 (P for linear trend <0.001). The upward trends were noted in both genders, all ages, rural/urban settings, and education groups (all P for linear trend <0.001), with greater increments in men, participants aged 18–64 years, and rural residents (P for interaction terms survey × sex, survey × age, and survey × rural/urban settings were 0.042, 0.003, and < 0.001, respectively). Trends in the prevalence of central obesity were similar when a more stringent BMI < 23 kg/m2 cut point (Asian cut point) was applied. Central obesity is associated with a higher risk of incident hypertension within normal BMI category. More than 65% individuals with obesity would be missed if solely BMI was measured.

Conclusions

We observed an upward trend in the prevalence of central obesity among participants with normal BMI irrespective of sex, age, rural/urban settings, and education level. Central obesity is associated with a higher risk of incident hypertension within normal BMI category. Approximately two thirds of the individuals with obesity would be missed if WC was not measured. It is, therefore, urgent to emphasize the importance of WC as a measure to monitor the prevalence of obesity.

Keywords:
Body mass index; Waist circumference; Central obesity; General obesity; CHNS