Elsevier

The Lancet

Volume 398, Issue 10294, 3–9 July 2021, Pages 53-63
The Lancet

Articles
Body-mass index and obesity in urban and rural China: findings from consecutive nationally representative surveys during 2004–18

https://doi.org/10.1016/S0140-6736(21)00798-4Get rights and content

Summary

Background

In China, mean body-mass index (BMI) and obesity in adults have increased steadily since the early 1980s. However, to our knowledge, there has been no reliable assessment of recent trends, nationally, regionally, or in certain population subgroups. To address this evidence gap, we present detailed analyses of relevant data from six consecutive nationally representative health surveys done between 2004 and 2018. We aimed to examine the long-term and recent trends in mean BMI and prevalence of obesity among Chinese adults, with specific emphasis on changes before and after 2010 (when various national non-communicable disease prevention programmes were initiated), assess how these trends might vary by sex, age, urban–rural locality, and socioeconomic status, and estimate the number of people who were obese in 2018 compared with 2004.

Methods

We used data from the China Chronic Disease and Risk Factors Surveillance programme, which was established in 2004 with the aim to provide periodic nationwide data on the prevalence of major chronic diseases and the associated behavioural and metabolic risk factors in the general population. Between 2004 and 2018 six nationally representative surveys were done. 776 571 individuals were invited and 746 020 (96·1%) participated, including 33 051 in 2004, 51 050 in 2007, 98 174 in 2010, 189 115 in 2013, 189 754 in 2015, and 184 876 in 2018. After exclusions, 645 223 participants aged 18–69 years remained for the present analyses. The mean BMI and prevalence of obesity (BMI ≥30 kg/m2) were calculated and time trends compared by sex, age, urban–rural locality, geographical region, and socioeconomic status.

Findings

Standardised mean BMI levels rose from 22·7 kg/m2 (95% CI 22·5–22·9) in 2004 to 24·4 kg/m2 (24·3–24·6) in 2018 and obesity prevalence from 3·1% (2·5–3·7) to 8·1% (7·6–8·7). Between 2010 and 2018, mean BMI rose by 0·09 kg/m2 annually (0·06–0·11), which was half of that reported during 2004–10 (0·17 kg/m2, 95% CI 0·12–0·22). Similarly, the annual increase in obesity prevalence was somewhat smaller after 2010 than before 2010 (6·0% annual relative increase, 95% CI 4·4–7·6 vs 8·7% annual relative increase, 4·9–12·8; p=0·13). Since 2010, the rise in mean BMI and obesity prevalence has slowed down substantially in urban men and women, and moderately in rural men, but continued steadily in rural women. By 2018, mean BMI was higher in rural than urban women (24·3 kg/m2 vs 23·9 kg/m2; p=0·0045), but remained lower in rural than urban men (24·5 kg/m2 vs 25·1 kg/m2; p=0·0007). Across all six surveys, mean BMI was persistently lower in women with higher levels of education compared with women with lower levels of education, but the inverse was true among men. Overall, an estimated 85 million adults (95% CI 70 million–100 million; 48 million men [95% CI 39 million–57 million] and 37 million women [31 million–43 million]) aged 18–69 years in China were obese in 2018, which was three times as many as in 2004.

Interpretation

In China, the rise in mean BMI among the adult population appears to have slowed down over the past decade. However, we found divergent trends by sex, geographical area, and socioeconomic status, highlighting the need for a more targeted approach to prevent further increases in obesity in the Chinese general population.

Funding

China National Key Research and Development Program, China National Key Project of Public Health Program, and Youth Scientific Research Foundation of the National Center for Chronic and Noncommunicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention.

Introduction

Obesity is a major risk factor for cardiometabolic diseases, renal disease, and many cancers,1, 2, 3, 4, 5 affecting 670 million adults worldwide in 2016.6 Globally, the prevalence of obesity in adults has almost tripled since 1975. In some middle-income countries, mean body-mass index (BMI) has increased by 5 kg/m2 and prevalence of obesity by more than ten times.6 In China, mean BMI and obesity have been increasing steadily since the 1980s following rapid economic development7, 8 but remained, at least by 2010, well below the levels seen in most other middle-income and high-income countries. Since 2010 national programmes targeting obesity and non-communicable disease prevention have been rolled out in China, including the National Demonstration Areas for Comprehensive Prevention and Control of Non-communicable Diseases and the China Healthy Lifestyle for All Initiative.9, 10 In 2013, the World Health Assembly also set an ambitious global target for control of non-communicable diseases, including to halt by 2025 the rise in the prevalence of obesity compared with 2010.11 Careful monitoring of long-term trends in BMI and obesity in general populations is essential to evaluate the likely success of various national and international initiatives and inform the development of country-specific health policies.

Research in context

Evidence before this study

We searched PubMed for studies on national trends in mean body-mass index (BMI) and obesity in China, published from Jan 1, 2010, to March 1, 2021, with no language restrictions, using the search terms ((obesity[MeSH Terms] OR (body mass index[MeSH Terms])) AND adult[MeSH Terms] AND China[MeSH Terms]) AND trend*[Title/Abstract]. We identified several studies that reported a rise in mean BMI and obesity in China until 2013 in both urban and rural areas and across different education groups. Evidence on trends after 2013 in BMI and obesity in China was mainly based on studies in particular regions and from statistical models in global studies. One study reported a steady rise in mean BMI and obesity (defined as BMI ≥27·5 kg/m2) among adults aged 18–80 years during 1993–2015. Another study found increasing trends in the prevalence of obesity (defined as BMI ≥28 kg/m2) among rural men aged 15–49 years during 2010–14. The use of the Chinese BMI cutoff for obesity in these studies, which was proposed in the early 2000s, restricted the ability to compare with data in China collected before 2004 or with data from other countries. The most recent study in China that classified obesity using the conventional WHO definition covered only a 5-year period during 2013–18 and found increasing prevalence; however, this study did not examine long-term trends before 2013, nor the trend in mean BMI. Furthermore, the study used an unconventioal sampling method, leading to an unexpected much lower obesity prevalence than reported in other nationwide surveys in China. To our knowledge, there are no national studies covering a prolonged time period in the years after 2015 for mean BMI or the prevalence of obesity using internationally comparable definitions (BMI ≥30 kg/m2) in China.

Added value of this study

To our knowledge, the present study provides the most up-to-date analyses of long-term and more recent trends in mean BMI and obesity prevalence in China. By using six large national surveys during 2004–18, we examined BMI and obesity prevalence both nationally and by sex, age, urban–rural locality, education, occupation, and geographical region. Our study showed that, in contrast to previous predictions, the increase in mean BMI and obesity prevalence appeared to slow down in China after 2010, when a number of large nationwide prevention programmes targeting non-communicable diseases and obesity were rolled out. However, there were divergent trends in urban and rural areas, particularly among women. Since 2010, the increase in mean BMI and obesity prevalence slowed down substantially in urban men and women, and moderately in rural men, but continued steadily in rural women. By 2018, mean BMI was higher in rural than urban women, but remained lower in rural than urban men. Among women, the mean BMI was persistently lower in those with higher education than in those with lower education across all six surveys, but the inverse was true among men. In China, 85 million adults aged 18–69 years (48 million men and 37 million women) were obese in 2018, representing a more than three-times increase since 2004.

Implications of all the available evidence

Although the total number of adults who were obese reached 85 million in 2018, the rise in mean BMI and obesity appeared to be slowing down in urban China, while in rural China BMI and obesity continued to rise, especially among women. In addition to divergent trends in urban and rural areas, there were also large disparities in BMI and obesity trends by sex, age, and socioeconomic status. Although further monitoring is needed to assess the longer-term trends and changing patterns, the present study findings highlight the pressing need for more targeted health policies to reduce further increases in obesity in the general population, with a gradual shift towards placing more emphasis on rural populations.

Some studies have previously reported on the rising trend in BMI and obesity prevalence in China, but these mainly used national survey data collected before 2013,12, 13, 14, 15, 16, 17, 18, 19 including some global pooling studies,6, 20 and tended to define obesity differently from the definitions used in most international studies.21 The paucity of reliable data on China's recent trends in mean BMI and obesity, both nationally and subnationally, for example, by urban–rural locality, which would reflect different stages of socioeconomic development, has led to substantial uncertainty over whether the rise in BMI will continue persistently. Moreover, important questions also persist concerning whether the rising trends in BMI might vary between men and women, urban and rural areas, or by socioeconomic or education status, which could inform more targeted intervention measures.

To address this evidence gap, we present detailed analyses of relevant data from six consecutive nationally representative health surveys done between 2004 and 2018. We aimed to examine the long-term and recent trends in mean BMI and prevalence of obesity among Chinese adults from 2004 to 2018, with specific emphasis on changes before and after 2010 (when various national non-communicable disease prevention programmes were initiated), assess how these trends might vary by sex, age, urban–rural locality, and socioeconomic status, and estimate the number of people who were obese in 2018 compared with 2004.

Section snippets

Survey design and populations

We used data from the China Chronic Disease and Risk Factors Surveillance (CCDRFS) programme, which was established in 2004 with the aim to provide periodic nationwide data on the prevalence of major chronic diseases and the associated behavioural and metabolic risk factors in the general population. Details of the design, objectives, and survey methods of the CCDRFS have been described elsewhere,22, 23, 24 and are summarised in the appendix (pp 3–5). Briefly, the CCDRFS was incorporated into

Results

Between 2004 and 2018, the number of participants included in each CCDRFS survey increased from 32 793 to 155 413, with increasing proportions of older people (mean age increased from 44 years to 52 years; ptrend=0·0070) and urban residents (12 295 [38%] to 70 861 [46%]; ptrend=0·0011; table 1). A higher proportion of participants performed non-manual work in 2018 compared with 2004 (6481 [20%] to 58 769 [38%]; ptrend=0·0277), whereas the inverse was true for agriculture-related work (18 569

Discussion

Using large-scale data from six nationally representative population surveys covering a period from 2004 to 2018, the present study showed that, although the prevalence of obesity has more than doubled and the total number of adults who were obese has more than tripled since 2004, there are divergent trends in urban and rural areas, especially among women. In urban China, the rise in adult BMI and obesity might be plateauing in women and slowing down in men, but in rural China continues to rise

Data sharing

Individual participant data in our study will not be made available publicly. For further detailed data access policy and procedure, please contact [email protected].

Declaration of interests

We declare no competing interests.

References (63)

  • Y Wang et al.

    Prevention and control of obesity in China

    Lancet Glob Health

    (2019)
  • C Ni Mhurchu et al.

    Body mass index and cardiovascular disease in the Asia-Pacific region: an overview of 33 cohorts involving 310 000 participants

    Int J Epidemiol

    (2004)
  • G Whitlock et al.

    Body-mass index and cause-specific mortality in 900 000 adults: collaborative analyses of 57 prospective studies

    Lancet

    (2009)
  • D Wormser et al.

    Separate and combined associations of body-mass index and abdominal adiposity with cardiovascular disease: collaborative analysis of 58 prospective studies

    Lancet

    (2011)
  • W Zheng et al.

    Association between body-mass index and risk of death in more than 1 million Asians

    N Engl J Med

    (2011)
  • Worldwide trends in body-mass index, underweight, overweight, and obesity from 1975 to 2016: a pooled analysis of 2416 population-based measurement studies in 128·9 million children, adolescents, and adults

    Lancet

    (2017)
  • Y He et al.

    Data resource profile: China National Nutrition Surveys

    Int J Epidemiol

    (2019)
  • B Zhang et al.

    The China Health and Nutrition Survey, 1989–2011

    Obes Rev

    (2014)
  • Y Jiang et al.

    Implementing the strategy of ‘Healthy China’ and strengthening the setting-up of national demonstration areas, for comprehensive prevention and control of non-communicable diseases

    Zhonghua Liu Xing Bing Xue Za Zhi

    (2018)
  • Global action plan for the prevention and control of noncommunicable diseases 2013–2020

    (2013)
  • H Wang et al.

    Trends in the distribution of body mass index among Chinese adults, aged 20–45 years (1989–2000)

    Int J Obes

    (2007)
  • LM Jaacks et al.

    Age, period and cohort effects on adult body mass index and overweight from 1991 to 2009 in China: the China Health and Nutrition Survey

    Int J Epidemiol

    (2013)
  • T Dearth-Wesley et al.

    Under- and overnutrition dynamics in Chinese children and adults (1991–2004)

    Eur J Clin Nutr

    (2008)
  • B Xi et al.

    Secular trends in the prevalence of general and abdominal obesity among Chinese adults, 1993–2009

    Obes Rev

    (2012)
  • C Shen et al.

    Urban-rural-specific trend in prevalence of general and central obesity, and association with hypertension in Chinese adults, aged 18–65 years

    BMC Public Health

    (2019)
  • Y Chen et al.

    The prevalence and increasing trends of overweight, general obesity, and abdominal obesity among Chinese adults: a repeated cross-sectional study

    BMC Public Health

    (2019)
  • X Zhang et al.

    Geographic variation in prevalence of adult obesity in China: results from the 2013–2014 National Chronic Disease and Risk Factor Surveillance

    Ann Intern Med

    (2020)
  • Rising rural body-mass index is the main driver of the global obesity epidemic in adults

    Nature

    (2019)
  • S Ma et al.

    Trends in the prevalence of overweight, obesity, and abdominal obesity among Chinese adults between 1993 and 2015

    Int J Obes

    (2021)
  • G Yang et al.

    Mortality registration and surveillance in China: history, current situation and challenges

    Popul Health Metr

    (2005)
  • WH Zhao et al.

    Methodology and content of China Chronic Disease Surveillance 2010

    Chin J Prev Med

    (2012)
  • Cited by (274)

    View all citing articles on Scopus
    *

    Joint first authors

    Joint senior authors and contributed equally

    View full text