Childhood overweight and obesity in Canada: an integrative assessment - HPCDP: Volume 37-3, March 2017

Introduction

In recent years, there has been a shift away from the "eat-less-move-more" paradigm of excess weight towards one that recognizes the multifactorial etiology of obesity and the importance of integrating a full socioecological, or integrative, understanding of its associated risk and protective factors.^{Footnote 1} Given the persistently high levels of excess weight among Canadian children and youth,^{Footnote 2} an integrated appraisal of its associated factors may inform our understanding of the health of this population to assist with public health efforts. This broader perspective is one that the Centre for Chronic Disease Prevention has similarly adopted for a variety of Public Health Agency of Canada (PHAC) surveillance initiatives.^{Footnote 3Footnote 4Footnote 5Footnote 6}

In this status report, we provide an overview of the socioecological framework that is now guiding PHAC's ongoing surveillance efforts in the area of childhood overweight and obesity. This framework considers individual risk and protective factors (sociodemographic, lifestyle, psychosocial and early-life) through the lens of the life stage, levels of influence and environments in which these factors play a role (Figure 1). Building upon our recent reporting on trends in and sociodemographic factors associated with childhood obesity in Canada,^{Footnote 2} this work illustrates the remaining (lifestyle, psychosocial and early-life) risk and protective factors shown in this surveillance framework. This integrated appraisal of factors also links to childhood obesity reporting included in the Chronic Disease and Injury Indicator Framework (CDIIF),^{Footnote 4} which is an important PHAC resource to guide research, programs and policy in Canada.

Figure 1
Socioecological surveillance framework of childhood overweight and obesity: individual risk and protective factors, environment and level of influence

Methods

Data and data sources

We analyzed data from two population-based national health surveys for this paper: the Canadian Community Health Survey ([CCHS] Annual Component, 2014^{Footnote 7} and 2011-12,^{Footnote 8} and Mental Health Component, 2012^{Footnote 9}) and the Canadian Health Measures Survey ([CHMS], cycle 3, 2012/13^{Footnote 10}). We identified factors associated with excess weight within each survey, according to the levels of influence presented in Figure 1. Lifestyle factors included healthy diet, sugar-sweetened beverage consumption, physical activity, sedentary behaviour and sleep. Psychosocial and early-life factors included mood disorders and depression, self-perceived physical health, happiness, sense of community, trustworthy relationships and breastfeeding. The distribution of each factor according to sex, age group, income adequacy and weight status were examined, except for breastfeeding.

Statistical analyses

We classified weight status (normal, overweight, obese) using the WHO classification system,^{Footnote 11} and adjusted self-reported estimates using a correction factor.^{Footnote 12} We completed descriptive statistics using SAS Enterprise Guide version 5.1 (SAS Institute Inc., Cary, NC, USA). We weighted point estimates to reflect the Canadian household population and calculated 95% confidence intervals using bootstrap resampling methods.

Results and discussion

Lifestyle factors

Eating behaviours

A healthy diet provides the necessary nutrients for growth and development.^{Footnote 13} Healthy eating patterns and behaviours established in childhood form the foundation of life-long healthy eating.^{Footnote 14} In the absence of detailed and regularly collected measures of healthy eating, surveillance of food consumption and general meal behaviours among children provide our best proxy measures of healthy eating.^{Footnote 15} To that end, national-level data on the consumption of vegetables, fruit and sugar-sweetened beverages provide an indication of eating behaviours among Canadian children and youth.

Vegetable and fruit consumption is a validated proxy measure for diet quality;Footnote 15 the consumption of 5 or more servings of vegetables or fruits per day is suggestive of a healthy diet.Footnote 15,Footnote 16 Fewer than half of Canadian children and youth maintain a healthy diet (Table 1). Youth with better income adequacy and weight status consume a healthier diet (Table 1). While meal (breakfast, lunch, dinner) patterns of Canadian children are supportive of healthy dietary behaviours, the prevalence of breakfast consumption remained stable between 2002 and 2010, with 3 in 5 children between the ages of 11 and 15 years eating breakfast on weekday mornings.Footnote 13 Among children aged 11 years, 75% of boys and 69% of girls reported consuming breakfast, compared to 59% and 46% of boys and girls aged 15 years, respectively.Footnote 17

Children often choose snacks in lieu of meals, particularly through adolescence. However, it is encouraging that the percentage of children and youth consuming potato chips and sweets on a daily basis had decreased significantly from 2002 to 2010.^{Footnote 13} Limiting the consumption of sugary drinks is also encouraged as part of a healthy diet.^{Footnote 18Footnote 19} A substantial proportion of children and youth (17.2%, 95% CI: 13.3-21.2) are drinking soft drinks, fruit drinks or sports drinks daily (Table 1). Individuals with low income adequacy consume higher levels of such beverages than their higher income counterparts (Table 1).

All-movement behaviours

Over the course of the 24-hour day, people engage in activity of varying intensity: moderate-to-vigorous physical activity, light activity, sedentary behaviour and sleep. An exceptionally low proportion of Canadian children (Table 1) are obtaining the amount of physical activity recommended by Canadian guidelines.^{Footnote 20} Notably, guideline adherence appears to decrease with age (Table 1), while weight increases with age, as described in our earlier article.^{Footnote 2}

Sedentary behaviours, such as watching TV, playing passive video games and using a computer, have been associated with obesity.^{Footnote 21} Canadian children and youth engage in an average of 8.4 hours (95% CI: 8.3-8.5) of sedentary activity each day. Canadian sedentary behaviour guidelines provide cut-offs for screen-based behaviours in children,^{Footnote 22} and recent data^{Footnote 10} suggest that 48.1% (95% CI: 42.6-53.6) adhere to these recommendations (Table 1). Sleep is also associated with obesity in children, with short sleep duration identified as a risk factor for excess weight.^{Footnote 23} The data^{Footnote 10} suggest that approximately one-quarter of children and youth do not obtain adequate sleep (Table 1) based on the latest recommendations.^{Footnote 24} Furthermore, a significantly higher proportion of young children accumulate adequate sleep than youth (Table 1).

Source: Statistics Canada, CCHS 2014, ages 12-17, and CHMS 2012/13, ages 5-17. Abbreviations: CCHS, Canadian Community Health Survey; CHMS, Canadian Health Measures Survey; CI, confidence interval. Note: Estimates of physical activity guideline adherence by weight status were suppressed due to high variability.

Supportive environments, such as schools, are key venues for physical activity engagement. Between 2006 and 2011, there was a 57% increase in the number of schools in Canada with a fully implemented policy for daily physical education.Footnote 25 Active transport, or physically active means of transportation such as walking, can contribute to a child's daily physical activity; however, it is estimated that only one-third (32.5%) of children aged 11 to 15 years used active transportation to get to school.Footnote 26 A large majority of school administrators in Canada report that students have access to built environment resources such as bicycle racks (79%), change rooms (75%), outdoor facilities (89%) and gyms (84%) during and outside of school hours.Footnote 25 In 2010, approximately 24% of parents cited safety concerns as a barrier to children playing outside.Footnote 27 In the same year, 93% of parents said that public facilities and programs were available for their children, but a lower proportion (65%) said that these facilities and programs met their needs.Footnote 28

Psychosocial factors

Internal psychological state and external social (interpersonal) relationships are factors that can precede the development of obesity, as well as outcomes that may arise as a result of weight status.^{Footnote 29Footnote 30} As a result, people living with obesity are often affected by fear, anxiety and/or depression.^{Footnote 31} While youth report experiencing mood disorders or depression (4.0%, 95% CI: 3.3-4.8), findings do not demonstrate differences based on weight status (Table 2). Nevertheless, how individuals perceive their appearance, abilities and uniqueness can impact their weight status.^{Footnote 32} Recent data demonstrate that obese youth are less likely to report that they are in good health (Table 2). The stability of happiness across weight categories (Table 2), however, suggests that weight does not associate strongly with self-concept, as might be expected.^{Footnote 33}

With respect to external outlook, although social isolation has been associated with excess weight,^{Footnote 34} when we examined children's reported sense of community and having trustworthy relationships, we observed no significant patterns on the basis of weight status (Table 2). Nevertheless, these psychosocial factors are also early-life factors that can affect health and weight at later ages.^{Footnote 29}

Early-life factors

A mother's preconception weight and her weight gain during pregnancy are two important prenatal factors associated with childhood obesity.^{Footnote 35Footnote 36} Women with high weight gain during pregnancy were at higher risk of having large-for-gestational-age babies, while those with low weight gain were at high risk for preterm birth and small-for-gestational-age babies.^{Footnote 35} Recent estimates suggest that one-third of Canadian women entering into pregnancy were overweight or obese and slightly less than half (48.7%) of women were gaining more than recommended.^{Footnote 37} In addition, child resemblance to parental (mother or father) body weight has been shown to be a result of complex interactions between environmental and genetic factors.^{Footnote 36Footnote 38Footnote 39}

Breastfeeding has been associated with lower rates of childhood obesity, and a majority of women who gave birth within a hospital or clinic in Canada were offered help by a health care professional to initiate breastfeeding within a half hour of birth.^{Footnote 35Footnote 40} In Canada, a large majority of mothers reported having breastfed their child, with roughly a quarter doing so exclusively for the child's first six months of life (Table 2).

Source: Statistics Canada, CCHS—Mental Health Component, 2012; CCHS 2011-12; and CCHS—Annual Component, 2014. Data is for children ages 12-17. Abbreviations: CCHS, Canadian Community Health Survey; CI, confidence interval.

Maternal smoking during pregnancy was also associated with child weight, with a 2.26 (95% CI: 1.23-4.15) odds of childhood obesity.^{Footnote 41} Roughly 10.5% of pregnant Canadian women smoke daily.^{Footnote 35}

Conclusion

Childhood obesity is a complex health issue impacted by a number of socioecological factors. While differences in individual risk and protective factors were not apparent on the basis of excess weight in childhood (except for healthy eating), childhood obesity has been shown to track into adulthood,^{Footnote 42} where these impacts may be more visible. The ongoing surveillance of overweight and obesity in children and youth, as well as the factors impacting them, helps to inform an understanding of population trends that can benefit future health efforts.

Conflicts of interest

The authors declare that there is no conflict of interest.

Authors' contributions

All authors were involved in the conceptualization and interpretation of the study. DPR was involved in the analysis of the data, and DPR, KCR, EK and MTD were involved in the drafting of the manuscript.

References