Introduction and epidemiology of childhood obesity in China
High birth weight (>4000 g) is associated with increased risk of obesity; it is also associated with increased risk of obesity from childhood to early adulthood.1 Increasing body weight during childhood has an impact on clinical outcomes when children grow older. A large body size as of 5 to 6 months of age, and fast weight gain before 2 years of age are related to large body size at age 5 to 13 years.2 Combining birth weight and infant weight gain, together with the body mass index (BMI) of the mother, may allow early stratification of infants at risk of childhood obesity.3 The persistence of childhood obesity into adulthood correlates with increased cardiometabolic risk in adulthood; yet, risks for these outcomes were similar to persons who were never obese when obese children became non-obese during adulthood.4 It is therefore crucial that the epidemic of childhood obesity should be addressed early.
As a rapidly developing country, China’s disease burden includes non-communicable diseases (NCDs).5 The rise in NCDs is paralleled in increased health care costs.5 Increasing incomes allow for relative affordability of food, while mobility may likewise be more restricted in the urban setting, decreasing the need for exercise and physical activity. A recent meta-analysis estimated the prevalence of obesity to be around 10.2%, based on studies published between 2011 and 2015 and using international standards on cut-off points for BMI in children; it is recognized, however, that the overweight and obesity rates in different (rural) parts of China may need further study.6
This meta-analysis also pointed out that parental education is important to tackle the problem. Parental contribution to childhood body weight issues is indeed increasingly recognized in the literature. Parental socioeconomic status, education, physical activity, attitude to body weight as well as smoking, have been correlated with childhood obesity.7,8,9 The causality of these factors is further buttressed by studies that show how parental intervention can improve children’s weights, such as behavioral change techniques and family counselling.10,11
This article reviews the parental contribution to body weight in childhood with respect to the Chinese population.
The relationship between parents and their children’s body weight12
In 2013, researchers from the Shanghai Jiao Tong University performed a cross-sectional study on Gao Hang Town, Shanghai. Focusing on primary schools, the study included 2,025 children aged 7 to 13 years, and their parents. This number represented 35% of the number of primary school children in the town.
Professional medical staff was employed to perform anthropometric measurements on children and their parents. Demographic data were also collected, including age, sex, breast feeding history and birth weight.
The total prevalence of overweight in children was 27.2% in this study population. The males had higher prevalence of overweight/obesity than the females: boys (35.5%), girls (19.5%), fathers (50.6%) and mothers (18.9%). Parents were divided into four subgroups according to their BMI: both parents with normal BMI; father overweight and mother normal BMI; father normal BMI and mother overweight; both parents overweight. In families where both parents were overweight, there was a strong correlation (odds ratio [OR] of 4.36; 95% confidence interval [CI]: 3.16, 6.01) with the children being overweight, compared to families with normal BMI parents. When only one of the parents was overweight, the OR of being overweight for the children was lower, with the OR being slightly higher in the families with a mother being overweight: 2.71 (95% CI: 1.87, 3.92) with overweight mothers versus 2.26 (95% CI: 1.78, 2.86) with overweight fathers, yet not statistically different from each other.
This study strongly suggests that parental body weight influences their children’s body weight. Being the same household with their children would imply that eating habits may be learned from either parent. Exposure to the same obesogenic diets may also be a likely factor contributing to this correlation.
Does this correlation extend to pregnancy weight? The next study will discuss this particular issue.
Gestational pregnancy and childhood body weight: Is there a correlation?13
The evidence for the correlation between gestational pregnancy and childhood body weight is conflicting. It was for this reason that Hong-Tao Tie and colleagues (2014) decided to perform a systematic review of these studies in order to get a glimpse of the bigger picture behind the varied results of the evidence.
The researchers performed a comprehensive search of research databases and literature. After a period of screening for the appropriateness and validity of these papers, twelve cohort studies were included in the final analysis.
Upon performing the meta-analysis, the combined OR of obesity in children of mothers with excessive gestational weight gain was statistically significant at 1.33 (95% CI: 1.18, 1.50). There was significant heterogeneity with this result (I2 = 71.1%). When other factors were controlled, such as maternal BMI, investigation area, and age of children, there was little influence in the OR. Eliminating publication bias yielded an OR that was still statistically significant at 1.21 (95% CI: 1.05, 1.40).
This relationship has also been demonstrated in the Chinese population. A study by Guo and colleagues (2015) on more than 100,000
mother-child pairs from the Zhejiang and Jiangsu southern provinces yielded an OR for obesity and overweight in children among mothers with excessive gestational weight gain of 1.21 (95% CI: 1.12, 1.29).14 The OR was even higher if the mother was obese/overweight before pregnancy and still had excessive gestational weight gain, at 2.22 (95% CI: 1.79, 2.76).
Clearly, childhood body weight is influenced by the weight of their mothers even while these children are in the womb.
What other parental factors influence childhood body weight?15
A systematic review was performed examining parenting styles and their correlation with childhood obesity and overweight. The findings showed that neglectful or uninvolved parenting styles increase the risk of childhood obesity and overweight. The same was true for indulgent parenting styles, when compared to authoritarian parenting. Overprotectiveness also correlated with childhood obesity and overweight. However, when the child perceived parents to be more responsive and demanding, weight tends away from obesity and overweight.
Indulgent feeding styles increased the risk for childhood obesity and overweight. Restrictive and controlling feeding practices initially controlled the weight of young children, but this protective effect disappears when these children enter their teenage years. More importantly, extremes of completely allowing snacks to complete control of snacks both led to increase in the weights of children. When encouragement to eat healthy food was introduced, body weight of children fell within normal range.
This systematic review illustrates the value of being moderate in feeding and parenting styles, favoring more positive forms of influencing what children eat instead of extreme interventions.
Parental interventions to address excess childhood body weight
External interventions are frequently advised by physicians and other health care professionals. However, the evidence for the effectiveness of these interventions varies.16
Face-to-face and telephone counselling with parents were both found to be effective at changing the diet of children, but not for physical activity.16 For more concrete changes in body weight of children, group counselling with other parents had greater effect than one-on-one counselling. This correlation was stronger in families of lower socioeconomic status.
A study in Shanghai demonstrated short-term benefits of a summer camp for weight management targeting obese children and adolescents.17 The 4-week camp focused on personal behavior such as energy-restricted diets and supervised physical activity. There was a weight loss of 7.2 ± 2.2 kg and reduction in BMI by 2.9 ± 0.9 kg/m2.
Performing joint interventions with parents and kids together may be another strategy. This was explored in a study performed in Hefei, Anhui, China.18 The study randomized 1,902 children from four different kindergarten classes in the city to either nutrition education activities or no nutrition education activities. These activities were formed with both parents and children present at the same time. After one year, parental and children’s eating habits significantly improved, with better lifestyle behavior noted. Parental attitudes and planning patterns also changed for the better. However, there were no statistically significant changes in the children’s weights at the end of the study.
The obesity epidemic in children clearly starts from the womb, and is perpetuated by parents in early life. Interventions to address this epidemic have mixed results, and a customized plan for each family may be the best way to benefit from the available evidence.
Special focus must also be given to developing countries like China, where the epidemic may eventually explode into an adult population burdened by the complications of obesity.
- Yu ZB, et al. Birth weight and subsequent risk of obesity: a systematic review and meta-analysis. Obesity Reviews. 2011;12(7):525-542.
- Stocks T, et al. Body size and growth in 0- to 4-year-old children and the relation to body size in primary school age. Obes Rev. 2011 Aug;12(8):637-52. Epub 2011 Mar 23.
- Druet C, et al. Prediction of childhood obesity by infancy weight gain: an individual-level meta-analysis. Paediatric and Perinatal Epidemiology. 2012;26(1):19-26.
- Juonala M, et al. Childhood Adiposity, Adult Adiposity, and Cardiovascular Risk Factors. N Engl J Med. 2011; 365:1876-1885.
- Xiao N, et al. A community-based approach to non-communicable chronic disease management within a context of advancing universal health coverage in China: progress and challenges. BMC Public Health. 2014;14(Suppl2):S2.
- Tian Yue & Wu Haixia (2015). Food & Nutrition Research 2015, 59: 25747. Prevalence of obesity among students aged 6 to 12 in China: a meta-analysis.
- Sleddens EF, Kremers SP, Hughes SO, Cross MB, Thijs C, De Vries NK, O’Connor TM. Physical activity parenting: a systematic review of questionnaires and their associations with child activity levels. Obes Rev. 2012;13:1015-33.
- Scaglioni S, Arrizza C, Vecchi F, Tedeschi S. Determinants of children’s eating behavior. Am J Clin Nutr. 2011;94: 2006S-11S.
- Hawkins SS, Law C. A review of risk factors for overweight in preschool children: a policy perspective. Int J Pediatr Obes. 2006;1:195-209.
- van der Kruk JJ, Kortekaas F, Lucas C, Jager-Wittenaar H. Obesity: a systematic review on parental involvement in long-term European childhood weight control interventions with a nutritional focus. Obes Rev. 2013;14:745-60.
- Hingle MD, O’Connor TM, Dave JM, Baranowski T. Parental involvement in interventions to improve child dietary intake: a systematic review. Prev Med. 2010;51:103-11.
- Wan Y, et al. Is parental body weight related with their children’s overweight and obesity in Gao Hang Town, Shanghai? Asia Pac J ClinNutr 2015;24(3):509-514
- Tie H-T, et al. Risk of childhood overweight or obesity associated with excessive weight gain during pregnancy: a meta-analysis. Arch Gynecol Obstet. 2014;286(2):247-257.
- Guo L, et al. Gestational Weight Gain and Overweight in Children Aged 3–6 Years. J Epidemiol 2015;25(8):536-543
- Shloim N, et al. Parenting Styles, Feeding Styles, Feeding Practices, and Weight Status in 4–12 Year-Old Children: A Systematic Review of the Literature. Frontiers in Psychology. 2015;6(01849).
- Kader M, et al. Effectiveness of universal parental support interventions addressing children’s dietary habits, physical activity and bodyweight: A systematic review. Prev Med. 2015 Aug;77:52-67. Epub 2015 May 14.
- Tang Q, et al. Effects of a summer program for weight management in obese children and adolescents in Shanghai. Asia Pac J Clin Nutr 2014;23(3):459-464.
- Hu C, et al. Evaluation of a kindergarten-based nutrition education intervention for pre-school children in China. Public Health Nutr. 2010 Feb;13(2):253-60. Epub 2009 Aug 4.