The link between obesity rates and sociodemographic characteristics, such as income, education, and ethnicity have been investigated time and time again, but what about the impact of “place” on obesity rates? The latest issue of the American Journal of Preventive Medicine seeks to explain the role of “obesogenic and leptogenic environments” in pediatric obesity (1) . Could your neighbourhood and surrounding environment potentially sabotage your weight? If so, can we design communities that effectively reduce obesity, particularly in children?
The recent article from Wang et al. (2), which established caloric reductions to reach the Healthy People 2010 and 2020 goals, has gotten a lot of press and for good reason – it lays out specific numerical goals to reduce pediatric obesity, in a way that can be easily translated. Interestingly, the remainder of the geography-focused issue of American Journal of Preventive Medicine, focuses on novel studies relating where people live and the environmental exposures that accompany their living situations to the pediatric obesity epidemic.
Researchers in this series look at both sides of the energy balance equation – nutrition and physical activity – by defining neighbourhoods as “high nutrition” (supermarket nearby but reduced fast food outlets), “low nutrition” (no supermarket nearby but ample access to fast food outlets), “high physical activity” (high area “walkability” and access to nearby high-quality park), “low physical activity” (low area “walkability” and no access to nearby high-quality park). These environments were then used to devise 4 different neighbourhood types (3):
- high nutrition and high physical activity
- high nutrition and low physical activity
- low nutrition and high physical activity
- low nutrition and low physical activity
Which do you think was related to reduced risk of obesity? Saelens et al. (4) found that children living in neighbourhoods with better access to fresh food and more supportive of activity (high nutrition/high physical activity) were 59% less likely to be obese when compared to those living in low nutrition/low physical activity areas. Interestingly, this association persisted even when socioeconomic status (SES) demographics like family income were controlled for, suggesting this was not simply about financial status. Low rates of perceived safety, likely related to high rates of crime, were positively correlated with increased body weight, especially in young teens; both genders had higher BMIs when safety during the day and night was a concern (5).
High level of access to fast food = higher body weight
Greater access to away-from-home eating (restaurants, fast food, and convenience stores) was associated with increased BMI, particularly in girls (5,6). When frequency of fast food intake increased, so did BMI and risk of obesity (5). This is not surprising given the established relationship between energy-dense, nutrient-poor food choices and risk of obesity and chronic disease.
“I had to walk 5 miles, uphill, in the snow every day to school…”
Turns out those children who “actively commute” to and from school each day have a reduced risk of obesity. Rainham et al. (7) tracked the activity of 316 adolescents (12-14 year olds) over a three-day period with GPS and accelerometers and found that the majority of moderate-to-vigorous activity (MVPA) in children was related to active commuting (> 50% of MVPA) to and from school, whether walking or biking in an urban/suburban setting. Activity at school and home accounted for additional 30% each, with the remaining 10% of activity occurring at other locations such as malls, parks and athletic facilities.
So, what does it all mean? Given that relationships between neighbourhood characteristics persisted even when SES factors like ethnicity, income and parental education were controlled for, the importance of immediate living environment is an important predictor of obesity risk. While many obesity-reduction programs target obesity at the individual or school level, this new research indicates that city planning will play a crucial role in reducing pediatric obesity through:
- improved park and green space access
- accessibility of supermarket locations
- distribution of fast food and convenience stores
- usability of public transit
- prioritizing pedestrian/cyclist paths, particularly in areas dominated by busy streets and “highways”
- crime reduction and safety initiatives
Again, it just goes to show how multifactorial the obesity epidemic is AND how important a multidisciplinary approach will be to success!
- Matthews SA. Thinking about place, spatial behavior, and spatial processes in childhood obesity. Am J Prev Med 2012; 42: epub ahead of print.
- Wang YC, Orleans T, Gortmaker SL. Reaching the Healthy People goals for reducing childhood obesity: closing the energy gap. Am J Prev Med 2012; 42: epub ahead of print.
- Frank LD, et al. Objective assessment of obesogenic environments in youth: geographic information system methods and spatial findings from the Neighborhood Impact on Kids study. Am J Prev Med 2012; 42: epub ahead of print.
- Saelens BE, et al. Obesogenic neighborhood environments, child and parent obesity: the Neighborhood Impact on Kids study. Am J Prev Med 2012; 42: epub ahead of print.
- Wall MM, et al. Patterns of obesogenic neighborhood reatures and adolescent weight: a comparison of statistical approaches. Am J Prev Med 2012; 42: epub ahead of print.
- Fraser LK, Clarke GP, Cade JE, Edwards KL. Fast food and obesity: a spatial analysis in a large United Kingdom population of children aged 13-15. Am J Prev Med 2012; 42: epub ahead of print.
- Rainham DG, et al. Spatial classification of youth physical activity patterns. Am J Prev Med 2012; 42: epub ahead of print.