Built environment and childhood obesity

Abstract

Childhood obesity, an escalating global health challenge, is intricately linked to the built environment in which children live, learn, and play. This review and perspective examined the multifaceted relationship between the built environment and childhood obesity, offering insights into potential interventions for prevention. Factors such as urbanization, access to unhealthy food options, sedentary behaviors, and socioeconomic disparities are critical contributors to this complex epidemic. Built environment encompasses the human-modified spaces such as homes, schools, workplaces, and urban areas. These settings can influence children’s physical activity levels, dietary habits, and overall health. The built environment can be modified to prevent childhood obesity by enhancing active transportation through the development of safe walking and cycling routes, creating accessible and inviting green spaces and play areas, and promoting healthy food environments by regulating fast-food outlet density. School design is another area for intervention, with a focus on integrating outdoor spaces and facilities that promote physical activity and healthy eating. Community engagement and education in reinforcing healthy behaviors is necessary, alongside the potential of technology and innovation in encouraging physical activity among children. Policy and legislative support are crucial for sustaining these efforts. In conclusion, addressing the built environment in the fight against childhood obesity requires the need for a comprehensive, multipronged approach that leverages the built environment as a tool for promoting healthier lifestyles among children, ultimately paving the way for a healthier, more active future generation.

Key Words: Non-communicable diseases; Walkability; Playgrounds; Neighborhood green spaces; Safety; Pollution

Core Tip: Prevention of obesity must begin in childhood. Healthy habits and physical activity form the cornerstone. Built environment, the environment in which children grow, play, and eat, must encourage a healthy lifestyle. Studies show critical aspects of the built environment are important for improving children’s health and for preventing metabolic diseases.

INTRODUCTION

Obesity transitioned from being a cosmetic problem to a health condition. A 2021 report from the World Health Organization stated that the prevalence of obesity globally has increased nearly three-fold since 1975[1-6]. This was seen across age groups, with differences observed across geographies[7-10]. Built environment includes homes, schools, urban areas, and access to leisure activities; it has a role in the risk of childhood obesity. Efforts are needed to develop built environments that aid in a healthy lifestyle to prevent diseases later in life.

RISK FACTORS

Although genetics and environmental factors have a role in the pathogenesis, the galloping increase over a short time period points to the overwhelming role of environment. Since childhood obesity is the precursor of obesity in adulthood with its attendant morbidities, prevention is paramount[11]. The first step is to understand the lifestyle factors that lead to obesity, which can then be addressed.

One of the proposed theories for increasing obesity in low-income and middle-income countries is the ‘modernization theory.’ The ‘dependency/world systems theory view’ proposes that primarily external structural factors are responsible for the rising obesity trends (e.g., flooding countries with obesogenic, nutrient-poor foods). Fox et al[12] compared the dependency theory and modernization theory and found the latter was more likely responsible. Modernization theory states that countries economic progress passes through phases where nutrition transitions occur from a lower calorie, chiefly plant-based diet to a meat and processed food diet that leads to weight gain and attendant comorbidities. There was a global association between urbanization rate and childhood overweight and obesity[12].

These trends were attributed to global economic development, cultural differences, and intergeneration effects of malnutrition in early life. Countries with the most rapid growth shared rapid economic development and social and cultural changes leading to consumption of unhealthy ultra-processed foods. Reversal or stabilization of trends occurred due to governmental interventions as in Denmark[13].

Similarly, increasing sedentary habits resulting from access to electronic gadgets such as mobile telephones, televisions, and computers led to sedentary behavior. Together, increased energy intake and diminished physical activity contributed to the dramatic rise of childhood overweight and obesity[11]. Interventions must address these two factors.

BUILT ENVIRONMENT

Built environment, which refers to the environments that are modified by humans, including homes, schools, workplaces, highways, urban sprawls, accessibility to amenities, leisure, and pollution[14] has a role in influencing both arms of the energy equilibrium. Therefore, attention is increasingly drawn to aspects of built environment that can result in better lifestyle and positive health outcomes[15]. It is significant that obesity in childhood persists into adulthood. A broad-based approach at prevention is essential. Earlier studies showed that the place of living is a strong determinant of obesity. Built environment encompasses the physical built infrastructure in which people live and is a potential area for intervention[16]. It contributes by influencing the broader obesogenic environment, spreading out to the family and sociopolitical environment[17]. Behavioral changes encompass unhealthy diet intake at late hours, watching electronic media with resultant disruption in sleep times, and house, which can lead to adverse metabolic changes[18].

COMPONENTS OF BUILT ENVIRONMENT

A life-course approach to understanding childhood obesity shows key steps for intervention. Trasande et al[19] employed it to identify environmental factors encompassing the built environment and chemical environmental agents as correctable factors in preventing obesity. Interventions at the genetic level[20] are not possible yet. The importance of environment in childhood obesity has received focus[21]. Most of the obesogenic environmental factors associated with built environment were related to childhood obesity, including land-use mix, street connectivity, residential density, urban sprawl, access to green space, public transport, bike lanes, sidewalks, neighborhood aesthetics, access to convenience stores, supermarkets, grocery stores, full-service restaurants, fast-food restaurants, and fruit and vegetable markets[21]. Some of these factors were consistent on a global basis including greater access to fast-food restaurants in the neighborhood and more fast-food consumption, access to bike lanes and more physical activity, better access to sidewalks and reduced sedentary behaviors, and greater access to green space and less TV screen time.

While early life adverse events result in obesity by the age of 13 years[22], built environment can also affect the quality of life in children[23].

CONCEPT OF BUILT ENVIRONMENT

Built environment encompasses the physical structure as well as the built infrastructure where people live, work, play, learn, travel, and socialize[24]. Both vehicular traffic and environmental pollution are included in the term[16]. The scope has been expanded to include houses, roads, walkways, density, transportation networks, shops, parks, and public spaces as well as activities happening there[25,26].

To determine positive and negative aspects of built environment in children, two parameters are used: Active transport to school refers to walking or bicycling to school every day[26]; and safe routes to school includes provision of a safe and walkable environment that allows children to reach school in an active manner[26].

DETERMINANTS OF BUILT ENVIRONMENT

Ortegon-Sanchez et al[27] published a meta-narrative review on the measurement of different features of built environment and child health. In view of the heterogeneity inherent in published studies, a meta-narrative review approach was chosen to systematically review complex topics that were conceptualized and studied in different ways by different research groups[27]. The aim was to provide an understanding of the methods that were employed to study the complex interactions between the built environment and children’s physical and mental health. From the major databases (Scopus, MEDLINE, Embase and PSycinfo), 108 studies were included in the analysis. Four broad areas were assessed: Streets; built environment; health; and population.

Objective measurement of physical activity was positively associated with street connectivity, and density of residences, households, and population. It was linked to accessibility as well as objective and perceived closeness to activity. There was a dichotomy between perceived personal safety by the children and their parents.

In contrast, greater time spent in sedentary activities was associated with less walkability. Objective assessment of overweight and obesity were made in 30 studies by using body mass index (BMI). Lower BMI was reported with intersection density, walking paths, parks and play areas, convenience stores, and traffic safety. Higher BMI was related to access to food outlets, perceived risk of crime, and physical incivilities.

Broadly, ten areas were commonly studied: (1) Residential and population density; (2) Street connectivity; (3) Diversity of land-use; (4) Walkability, a composite of the above three factors; (5) Walking infrastructure and perception of street environment; (6) Proximity and accessibility to school and to play spaces; (7) Parks, green areas for physical activities; (8) Perceptions of safety; (9) Motor traffic levels; and (10) Social support and psychosocial factors[27].

Among these, a positive association with children’s health was observed with safety, street connectivity, access to play facilities, parks, and land-use diversity. However, there is no one-to-one cause and effect relationship. Different factors can act as enablers or inhibitors, and they interact, resulting in a complex and context-dependent cumulative impact on health measures[27]. This meta-narrative review was built upon the earlier 2010 publication by Galvez et al[28] that assessed diet, physical activity, active commuting, walkability, obesity, and neighborhood safety. These associations are in alignment with a recent systematic review using a geographic information system (GIS)[29]. Certain other factors were considered such as aesthetics, and physical activity[30]. The results suggested it is still a work in progress.

GLOBAL STUDIES ON BUILT ENVIRONMENT AND OBESITY

While optimal built environment has its greater potential in preventing obesity at an early age, most previous studies assessed interventions in adults across different geographical regions (Table 1)[31-34].

Table 1 Studies on the association of built environment and childhood obesity.

Ref.	Publication year	Association with childhood obesity
Sweden[35]	2017	Access to fast food outlets
Wales[36]	2021	Density of fast food outlets
Germany[38]	2020	Access to green spaces
New Zealand[41]	2016	School travel distance, green space
Durham (United States)[42]	2012	Housing location, safety
California (United States)[44]	2018	Green space, safety
New York (United States)[45]	2018	Fast food restaurant density
Montreal (Canada)[46]	2018	Pedestrian friendly areas, fast food outlets
Latin American nations[51]	2023	Urban isolation no association with population density or greenery
Shanghai (China)[57]	2023	Recreational and sports facilities
Bangalore (India)[59]	2019	Neighborhood walkability
Uganda (Africa)[61]	2021	Little relation to environmental characteristics

STUDIES ON CHILDHOOD OBESITY AND BUILT ENVIRONMENT

Europe

In a longitudinal study from Sweden, higher odds of childhood obesity were observed in children from neighborhoods with access to fast-food outlets [odds ratio (OR): 1.14, 95% confidence interval (CI): 1.07-1.22][35]. A cross-sectional study in Wales showed that even after adjusting for deprivation, associations were found between childhood obesity and percentage of land available as accessible open space (OR: 0.981, 95%CI: 0.973-0.989, P < 0.001) and density of fast food outlets (OR: 1.002, 95%CI: 1.001-1.004, P = 0.001). These risk factors must therefore be addressed[36].

Similar results were reported from England. There was a statistically significant relationship between the sales of unhealthy foods and the prevalence of overweight and obese children[37]. It was shown that deprivation was positively associated with weight (P < 0.001). The non-white population was negatively associated (P < 0.001) with overweight and obesity.

Zhou et al[38] presented data from Germany (22678 children in 51 administrative areas). Higher spatial availability of greenspace was associated with children’s risk of being overweight (OR: 0.989, 95%CI: 0.985-0.994), although this association failed to attain statistical significance (OR: 0.997, 95%CI: 0.992-1.003) after adjusting for other variables.

Oceania

In a review on the status of built environment and childhood obesity from Australia, there was a focus on the role of the built environment in supporting physical activity[39]. The built environments and child health in Wales and Australia (beaches) study incorporated longitudinal quantitative data (surveys, anthropometry, accelerometry, and GIS data) to assess the built environmental influences on children’s modifiable risk factors for non-communicable diseases[40].

The urban study from New Zealand studied the associations between neighborhood environment and walking in children[41]. Using GIS, 2016 households were selected from 48 Low-walkability and high-walkability neighborhoods from four cities in New Zealand. Children (n = 227) from the selected households wore accelerometers to record their physical activity in the period of 2008-2010. Two aspects were measured: (1) Factors that might affect physical activity and residential environment (school distance, amenities for recreational activity, food outlets, and outlets); and (2) Four audited environmental factors including pedestrian amenities, safety, aesthetics, and local destination. The former were assessed by GIS and the latter by SPACES.

The omni-directional piezo-electric sensor that can measure movements as step and accelerometer counts was worn by the children for 7 d. There was a dichotomy between environmental features and physical activity between school travel and non-school physical activity[41]. During school travel times, more activity was associated when the home distance was 1-2 km from school and the existence of green spaces and attractive streets. Areas with more food outlets showed a negative association with physical activity. These results were different from studies in adolescents for non-school physical activity[41]. The authors advised that parental assurance on safety of children must be addressed when developing built environment.

North America

North Carolina: In 2012, Miranda et al[42] studied the association between seven built environment domains and childhood obesity in Durham, North Carolina. Housing damage, property disorder, vacancy, nuisances, and territoriality were linked with the Duke University Medical Center pediatric preventive care visits (2008-2009). Children’s overweight and obesity were associated with nuisances and territoriality (P < 0.05). Similar associations were observed in adolescents from London[43].

California: In California, the relationship between social and physical environmental attributes of the school environment (within school and neighborhood) and childhood obesity was assessed using random forest and multilevel methods[44]. School obesity prevalence ranged from 0.0% to 75.0% [median of 19.8% (interquartile range = 11.5%) and mean of 19.7% (standard deviation: 7.8%)]. The percentage of socioeconomic disadvantaged ranged from 0.0% to 100.0% [median of 40.2% (interquartile range = 63.9%)]. The most highly ranked built or physical environment variables were distance to the nearest highway and greenness. Others were prevalence of violent crime, socioeconomic disadvantage, and fewer physical education teachers.

New York: Children from New York showed geographic disparities across local regions. The relationship between these differences with built environment was reported by Dwicaksono et al[45]. Association of obesity was found with higher fast-food restaurant density (unstandardized coefficient, b = 0.014; P < 0.05). Access to food sources was proposed to contribute to regional differences in childhood obesity[45].

Montreal, Canada: In Montreal, Canada, street-level urban design features were shown to shape childhood adiposity[46]. Data were obtained from the Quebec adipose and lifestyle investigation in youth study. The subjects comprised 630 children aged 8-10 years with a history of obesity in the family. Baseline measurements were recorded between 2005 and follow up between 2008 and 2011. Street-level urban designs such as pedestrian aids, physical activity facilities, convenience stores, and fast-food restaurants were shown to be modifiable features to prevent childhood adiposity[46].

New York City: In New York City, the relationship between fifth-grade students’ (n = 952) physical activity, psychosocial factors, and neighborhood built environment of the school was assessed[47]. The variables included park access, public transportation density, total crime, and walkability after controlling for age and BMI z-scores. Physical activity in boys was associated with public transportation density (β = 0.375; P = 0.02) and negatively associated with total crime (β = -0.216;P = 0.01). Frequency of light physical activity in girls was associated with park access (β = 0.188; P = 0.04). Built environment characteristics were able to account for 97% of the between-school variation in self-efficacy in walking for exercise in girls[47].

Denver: The relationship between systemic racism and obesity was studied in the Denver metropolitan region. Children aged 4-8 years (n = 250) were drawn from the healthy start cohort. Linear regression models were used to estimate associations between neighborhood features with child BMI z-scores and fat mass percent. A significant association was observed between child BMI and redlining (β: 1.36, 95%CI: 0.106-2.620). There was no association between walkability measures and childhood obesity. Therefore, inclusionary zoning and direct investments in neighborhoods must be assessed and repaired to improve the built environment and thereby children’s health status[48].

Longitudinal studies: In 2016, the United States launched a longitudinal analysis of the relationships between early life environment and later obesity among large diverse samples of children. The large sample size and the adoption of standardized methodology enables a refined analyses to identify drivers of childhood obesity[49]. An analysis of 20677 children from the cohorts showed that children from higher-opportunity and lower-vulnerability neighborhoods in early life showed a lower rate of BMI increase and a lower risk of obesity from childhood to adolescence[50].

South America

A cross-sectional analysis of a large group of children (n = 20040) living in 159 cities in six Latin American countries was carried out to assess the association between built and social environment and childhood obesity[51]. This study was important because preschool children were studied, unlike most other reports on school children and adolescents. Up to 97% of the variability was observed between individuals within sub-city units; about 3% of the variance in z-scores of weight for height was attributed to features at the city and sub-city levels. In cities, a greater distance between urban patches (isolation, per 1 standard deviation increase) was associated with lower odds of excess weight (OR: 0.90, 95%CI: 0.82-0.99). There was a significant variation in the prevalence of overweight and obesity (range: 4% to 25%). Cities from Chile had the highest prevalence, while cities in Columbia and Peru had the lowest prevalence. Unlike reports from developed countries, higher levels of urban isolation and education level lowered the odds of excess weight. Similarly, there was no association between excess weight in children and population density, intersection density, and presence of greenery[51]. The difference could be due to increased physical activity and greater perception of safety.

Asia

A scale to determine urban and rural areas was constructed in cities drawn from Asia and Africa (India and Ethiopia), in which built environment was a component[52]. The purpose was to identify factors responsible for geographical differences in the prevalence of non-communicable diseases. This scale was widely employed in the assessment of differences in health conditions[53-55].

China: A recent study from the city of Shanghai in China (2023)[56] showed that neighborhood built environment and outdoor leisure activity opportunities are important influences in the prevalence of obesity of children. Conducive built environment is a modifiable factor to reduce childhood obesity. The neighborhood built environment influenced children’s obesity not only directly (β = 0.15, P < 0.05) but also through the effect of outdoor leisure activities (β = 0.19, P < 0.05) in both boys and girls. A narrative systematic review was published on the impact of built environment and physical activity and obesity in children and adolescents from China (2019)[57]. Sixteen studies revealed a quantitative relationship between built environment and physical activity. Lack of recreational facilities, longer commuting time to sports facilities, and neighborhoods without sidewalks correlated with sedentary behavior[57]. These findings aligned with those from adults and from other countries.

Malaysia: An innovative method was employed to perform a spatial survey on overweight and obesity in Malaysia. The spatial smoothing methods for disconnected regions using split random effects and a common intercept showed a spatial pattern in the prevalence of childhood overweight across districts[58]. Complete BMI and geolocation information was available for 6301 children. The sample size varied widely between districts (0 to 363; median = 28). The national prevalence of overweight (including obesity) was 23.8% (95%CI: 22.2-25.4), the prevalence for boys was 24.5% (95%CI: 22.3-26.9), and the prevalence for girls was 23.0% (95%CI: 21.1-24.9). This study enabled identification of districts with a high prevalence of obesity, with an east to west gradient. Such information allows for corrective measures in precise geographical locations.

India: Devarajan et al[59] underlined the importance of modifying the obesogenic environment rather than leaving the responsibility to individuals. Apparently healthy school children from Bangalore (n = 292) aged 6-15 years were stratified, and the walkability index was derived using residential density, street connectivity, and land-use mix environment variables[60]. They concluded that neighborhood walkability may be associated with obesity indices in younger children

Africa

Uganda: A study from Uganda revealed local geographic differences of the association of built environment and physical activity. Nakabazzi et al[61] did not find a strong relationship between environmental characteristics and school children’s moderate-to-vigorous physical activity. Children’s moderate-to-vigorous physical activity was related to the availability of play equipment at home (β = -2.37, P < 0.001; unexpected direction), residential density (β = 2.70, P < 0.05), and crime safety (β = -5.29, P < 0.05; unexpected direction). The sex-specific analyses were inconsistent.

PERSPECTIVE

Traditionally, individuals were blamed for obesity in children for being sedentary. It is now increasingly being realized that environmental factors must be conducive for being physically active, i.e. the role of environmental determinants are responsible for health behaviors[57] (Table 2).

Table 2 Aspects of obesogenic environment and related factors¹.

Open spaces for physical activity
Access to unhealthy food outlets
Neighborhood and road safety
Air quality
Travel behavior
Family income

¹Adapted from Carmo et al[72] and Abdollahi et al[73].

Encouragingly, interdisciplinary work is carried out to predict the prevalence of physical inactivity. A recent study used spatial machine learning for predicting prevalence of physical inactivity[62]. While it is evident that neighborhood and health are related, there is little information on the relative importance of each component related to activity and the variability across geographic locations. The authors ranked seven socioecological neighborhood aspects to the prevalence of physical inactivity. As a first step, they employed geographical random forest, a nonlinear machine learning regression method to assess the variation and contribution of each predictive factor to physical inactivity. This was followed by its predictive performance being compared with geographically weighted artificial neural networks. The results determined that poverty was the most important determinant and green space the least important to physical inactivity in Chicago[62]. This information could be valuable in designing intervention strategies in other large cities.

POTENTIAL AREAS FOR INTERVENTION

Intervention studies were carried out to assess the impact of targeting school environment, street layout, traffic, and others. Vega-Salas et al[63] studied the effect of modifying the food built environments in and around schools from Latin America and the Caribbean. When complemented with nutritional and physical education, environmental intervention can reduce the trend of increasing childhood obesity. The specific effects and pathways of interventions need to be worked out by further studies.

Street-level built environment has a significant effect on health by acting through one’s ability to engage in healthy behaviors. There is evidence for improved built environmental factors having a positive impact in deprived areas. Ortegon-Sanchez et al[64] published a systemic review on whether these are applicable to high-income countries. Most interventions reported were temporary (e.g., closure of streets to traffic), while a few were permanent changes in street design. Subjects were aged below 18 years from high-income and upper middle-income countries. Outcomes recorded BMI or measures of activities.

The interventions, as mentioned earlier, were temporary and often ad hoc, carried out principally in summer months. Closure of streets were based on community preferences as were the physical activities. Permanent interventions consisted of making streets safe places to play. Although there are numerous factors interacting in improving physical activity, evidence is available that modifying the built environment is an achievable way to improve children’s health both in deprived areas and in children from high-income and upper middle-income countries. Further studies are needed to arrive at the types of changes in the built environment that result in the most significant health improvement[64].

A more comprehensive analysis of determinants that support active travel behaviors was published by Nordbø et al[65]. Among the 127 studies that were reviewed, 87.4% were cross sectional; the outcome of active travel was reported in 54. The authors concluded that the following could support active travel behavior: Less traffic; greater safety on roads; infrastructure enabling walking and cycling; shorter distance to facilities; and better walkability.

Evidence has been obtained from disparate and multidisciplinary sources. To contain the epidemic of childhood obesity, focused studies and data synthesis must lead to the employment of practical and effective methods of intervention.

SOLUTIONS TO BENEFIT LOW RESOURCE SETTINGS AND NATIONS

Most of the evidence comes from developed countries, whereas most populations reside in developing countries. How can aspects of built environment be applied to developing nations? It is important considering the increasing prevalence of non-communicable diseases due to urbanization, changes in lifestyle, and socioeconomic transitions; these can be addressed by modifying the built environment.

Planned urban development can prevent overcrowding and provide adequate public space and access to leisure time activities, thereby promoting an active lifestyle. In addition, access to healthy foods and limiting availability of fast foods helps create healthy eating opportunities.

Construction of houses with adequate ventilation that avoid overcrowding and allow access to clean water and sanitation are essential components. Access to public transportation prevents congestion on roads as well as vehicular pollution. The residential areas must be planned to allow green spaces that promote physical activity, reduce stress, and encourage social interactions, all of which mitigate the risk of loneliness (Table 3).

Table 3 Built environment aspects to be addressed in developing nations.

Green spaces and provision of spaces for physical activity
Availability and affordability of healthy dietary joints
Pedestrian paths for safe commute
Provision of facilities for playing sports and games
Safe walkability zones to go to school
Development of secure neighborhoods that encourage outdoor activities

These require collaboration and cooperation with both policy makers in the government and the residents of the locality. Implementation faces challenges including financial resources, increasing population, and in some nations political instability. With proper intention, these can all be overcome for the common good. On a broader scale, international funding and cooperation can be sought.

LIMITATIONS OF THE STUDY

The concept of modifying built environment to prevent childhood obesity is still emerging. Most studies were carried out on adults from developed countries. The current study is an attempt to bring the role of built environment to the attention of clinicians. It is a narrative review that gathered recent published studies on the role of built environment in childhood obesity. It also suggested potential ways in which it can be modulated for public good. This can plant the seed for further studies to provide solutions to improve built environment so that non-communicable diseases are prevented.

CONCLUSION

Built environment can be modified to reduce the burden of obesity. Interventions include enhancing active transportation by ensuring safe access to recreational facilities[66-68] and increasing availability of healthy food outlets. Technology can be used to monitor and reduce air pollution, a contributor to obesity[69-71]. These require policy and legislative support, a multi-dimensional challenge. By focusing on creating environments that naturally promote physical activity and healthy eating, we can foster healthier lifestyles for children to lay the foundation for a healthier future.

ACKNOWLEDGEMENTS

We thank Mr. Venkat Yarabati for assistance in the preparation of this manuscript.