Childhood obesity: what is happening in China?

Childhood obesity - A global public health problem

Childhood obesity - A global public health problem

by Dr Mu Li
CSC academic group: Health

Dr. Mu Li is an Associate Professor in international public health and the Academic Program Coordinator of the Master of International Public Health at the Sydney School of Public Health, The University of Sydney.

A medical graduate from China, her major teaching and research interests are public health nutrition. Dr Mu Li has an international reputation in iodine deficiency and iodine excess research, is a current board member of the International Council for the Control of Iodine Deficiency Disorders (ICCIDD). Between 1999 and 2005 Dr Li played a key role in the project of Iodine Deficiency Disorders Elimination in Tibet, China which saw thousands of newborns protected from lifelong consequences of brain damage associated with iodine deficiency disorders. Her other research interests include childhood obesity prevention and public health program evaluation. She is a chief investigator of a study in China to promote healthy infant feeding to prevent early onset of childhood obesity using modern media communication technologies and a chief investigator of a global study on food and beverage marketing targeted at children in East Asia, including China, and Southeast Asia. Dr Li is a member of the Editorial Board of the journal International Scholarly Research Network – Nutrition.

Childhood obesity - A global public health problem

High rates of childhood obesity have been evident for some time in many high income countries, such the USA, the United Kingdom and Australia. For example, in Australia, one in five children and adolescents are either overweight or obese. From 1985 to 1995 the number of overweight 7–15 year old Australian children almost doubled and the number of obese children more than tripled. At the current rate, it is predicted that 65 per cent of young Australians will be overweight or obese by 2020. In recent years some lower- and middle-income countries, including India, Indonesia and China have joined the trend. Such countries are experiencing a shift from under- to over-nutrition. As a result, the absolute number of children who are overweight or obese is now much higher in low- and middle-income than high-income countries, and they carry the larger share of the global burden of overweight children and childhood obesity.

Overweight children and childhood obesity are not simply shrugged off in adulthood; they have been linked to a raft of immediate and long-term adverse effects on health and well-being. The immediate effects include cardiovascular disease risks such as high cholesterol or high blood pressure; pre-diabetic and other health and psychosocial problems. Importantly, obese children have a 25-50% risk of progressing to obesity in adulthood. Overweight and obese children and adolescents are more at risk for adult non-communicable diseases such as heart disease, type 2 diabetes, stroke and several types of cancer.

Drivers of China’s childhood obesity epidemic

In the past three decades China has undergone unprecedented economic growth and development as evidenced by an average annual GDP growth of above 7% since 1990. Closely linked to this economic growth has been a process of nutrition transition and societal changes, both in speed and scale. Obesity, simply put, is the result of an imbalance between energy, i.e. calories consumed and expended. The nutritional and societal changes include: changing diets, not only the food composition but also the fact that more food is prepared away from home and energy-dense foods and drinks are readily available; rapid urbanisation with increased dependency on automobiles; reduced physical activity both at work and at home, which have all led to people either eating more or becoming less active and consequently increased the prevalence of overweight and obese Chinese adults and children.

There is an alarming trend of overweight and obese children in China:

  • The weight of Chinese children has increased markedly in the past 30 years.1
  • From 1986 and 2006, the overweight and obesity prevalence in Chinese children aged 7 or younger almost tripled.2
  • In 2010, about one in ten Chinese school-aged children and adolescents were overweight and a further one in twenty were obese. This means there were 30.4 million Chinese 7-18 year olds who were overweight or obese.3
  • Younger Chinese children have experienced larger increases in body mass index (BMI) in recent decades compared with those in the USA, the United Kingdom and Australia.4

The epidemiology of childhood obesity in China has some features that are distinctive from situations in most western countries, but resemble those in countries sharing similar cultural background, such as Thailand and Vietnam.

  • Difference in prevalence based on rural/urban residence, although the difference is shrinking since the year 2000.
  • Higher prevalence of overweight and obese children from households with higher economic status
  • Gender difference is relevant; the highest prevalence seen in younger boys.
quote In addition to the contemporary socio-economical factors, it has been suggested that the higher prevalence of overweight and obesity in boys is, at least, partially related to the traditional favoring of boys over girls, which is deeply rooted in the Chinese society.

The socioeconomic gradient, including the urban/rural disparity, of the prevalence suggests that the childhood obesity epidemic is driven by the environment and lifestyle the children are exposed to. In urban areas, it is common that both parents work full-time, having little time to prepare nutritious food at home. In particular, children from higher income families tend to eat out more, including eating Western-style fast food, and often have pocket money to buy snacks. Our study in Northeastern China has found that the snack foods children bought in or outside school with their pocket money were often high in sugar, fat and salt content. This is a different pattern from developed countries where childhood obesity is more prevalent in the lower socio-economic status families. In addition to the contemporary socio-economical factors, it has been suggested that the higher prevalence of overweight and obesity in boys is, at least, partially related to the traditional favoring of boys over girls, which is deeply rooted in the Chinese society.

In China, the increasing prevalence of overweight and obese school-aged children and adolescents is a combined effect of over-consumption of unhealthy foods and being physically inactive. The role of physical education in the school curriculum has been reduced. The primary aim of schools, often under pressure by children’s families, is for the child to excel academically in order to get into a ‘key’ (重点) high school and university. Some schools are struggling to keep physical education programs. Even breaks between classes are often taken up by teachers extending class time or giving children extra work, leaving them with little time to go outside. Many schools’ sports fields have been used for building extra classrooms to accommodate large student numbers, so there is simply no open space left for children to engage in physical exercise or play in the school. Increasing numbers of children, particularly in major cities, are being driven to and from school and have no time for outdoor physical activity after school. Our study in Northeast China has discovered that on average, 9-11 year old children spend 2.2 hours on school days doing homework and 1.2 hours watching television. On weekends and holidays they spend 2.9 hours doing homework, 3.2 hours attending extracurricular classes and 2.2 hours watching television. Essentially, children spend up to 7.0 hours during school days and more than 8.0 hours on weekend days sitting indoors studying or watching television.

In younger children, exclusively breastfeeding in the first six months of a child’s life, prolonging breastfeeding and engaging in appropriate infant feeding do not only improve under-nutrition but also prevent childhood obesity. The breastfeeding rate in China, however, has been declining in recent decades. The causes of the decline are multi-factual and complex. Chinese grandparents take great pride in a well-fed baby from the cultural and historical belief that a fat child symbolize prosperity of the family and, therefore, often push new mothers to switch to infant formula, which many of them could not afford to feed their own children when they were young. Many new mothers have been brought to believe their breast milk is insufficient to meet their children’s growth and development needs, both in quantity and quality. The latter has been largely influenced by the aggressive breast milk substitute advertisements and promotions to the effect that formula is superior to human breast milk. This not only shakes new mothers’ determination and confidence in breastfeeding their babies; it also puts them in a state of fear that they may deprive their babies of the “best” start in a very competitive society. Although China observes the World Health Organisation’s International Code for Marketing for Breast Milk Substitutes, there is a serious lack of enforcement and penalties for violating the Code. Many mothers are targeted during pregnancy, or while breastfeeding, by salespersons, media, and sometimes health professionals for breast milk substitute products. Breastfeeding is also a very private act in Chinese society. It is difficult for a young mother to breastfeed her baby in public places as there are very few private breastfeeding rooms. Many workplaces have not made it easy for women wanting to continue breastfeeding to return to work. The introduction and enforcement of the family planning policy, commonly known as the ‘one child policy’ since the late 1970s in China, coincides with the economic and nutrition transition. It has been suggested that under this policy the single child is often the subject of ‘overindulgence’ by two parents and four grandparents, being overfed and over-cared for.

We have developed a community-based health promotion program using media communication technology to promote breastfeeding and healthy infant feeding in Shanghai, aimed to reduce child body mass index at 2 years of age. The pilot indicates that the program is feasible and well accepted.

Economical and social implications if the trend continues

China is going through nutritional as well as an epidemiological transition, the disease burden shifting from communicable to non-communicable diseases. Amongst the adult population in China, being overweight and obese are now major risk factors for morbidity and mortality. The 2002 Chinese National Nutrition and Health Survey showed that the relative risk of developing hypertension and diabetes were between 2.3 and 5.2 higher in overweight and obese adults than in those with normal body weight.5 It is estimated that 92 million Chinese adults have type 2 diabetes, with a further 148 million being pre-diabetic.6

quote Obesity is of great importance from a health-policy perspective because of its prevalence in the population and the costs of treating the associated medical conditions in both the short and long term. However, the emergency of an overweight and obese population is as much an economic issue as well as a public health issue.

Obesity is of great importance from a health-policy perspective because of its prevalence in the population and the costs of treating the associated medical conditions in both the short and long term. However, the emergency of an overweight and obese population is as much an economic issue as well as a public health issue. Under the current Chinese health issuance schemes, most of the direct medical costs of obesity and related health problems are borne by individuals and their families, many of which cannot afford them. People suffering from obesity and related health problems also consume more health services which will exert extra demand on the health system. Based on adult body mass index data, it was estimated that 3.6% of the 2000 Chinese Gross National Product (GNP) and 8.7% of the 2025 Chinese GNP will be spent on obesity and its associated problems.7 The rapidly growing childhood obesity epidemic in China means that there will be a much higher cost to the individuals and to the society as a whole in the future due to lose of productivity and human capacity, if the trend is not curbed urgently. This urgency should underscore future research focus for effective interventions to prevent childhood obesity and future health policy for an enabling environment.

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7 Yang WY, Lu JM, Weng JP, Jia WP, Ji LN, Xiao JZ, et al. (2010). Prevalence of Diabetes among Men and Women in China. New England Journal of Medicine, 362(12): 1090-101.
8 Popkin B, Kim S, Rusev E, Du S, Zizza C. (2006). Measuring the full economic costs of diet, physical activity and obesity-related chronic diseases. Obes Rev, 7(3): 271-93.