Abstract:
The main purpose of this research is to describe how social and economic structures operating at different scales of influence have an impact on population overweight and obesity, and become manifest at the individual level. A mixed methods approach was used in this series of studies which facilitated a cross-scale analysis of the ecology of overweight and obesity, through linking of data at the individual and structural levels. Study one employed a cross-sectional retrospective analysis of overweight, obesity and socio-demographic indicators for 8,970,590 Canadian adults (25-64 years) using the 2005 Canadian Community Health Survey. Study two analyzed the trajectory of the energy gap (energy imbalance) in the Canadian population from 1976 to 2003, its temporal relationship to adult obesity, and estimated the relative contribution of energy consumption and expenditure to the increasing energy gap. It also assessed which foods contributed the most to changes in energy consumption over the study period. Study three used grounded theory to examine the etiology of working mothers’ food choice and food provisioning decisions. The research was informed by theoretical perspectives on the ecology of obesity, embodiment and structuration. The results of this series of studies show that:
1. There are significantly higher rates of overweight and obesity in some Canadian sub-populations. Despite these differences, the prevalence of overweight and obesity is very high in all socio-demographic groups, and focusing prevention interventions in the sub-populations with higher rates would do little to decrease overall population prevalence.
2. The energy gap in Canada has widened significantly in the past two decades along with population rates of obesity. Increased energy available through the food supply is a more important driver of obesity than decreased levels of physical activity.
3. Employed mothers, who are primarily responsible for family food, frequently make poor nutritional choices for themselves and their families which increase the risk of developing poor nutritional outcomes such as overweight and obesity. Despite their desire to provide more healthy food for their family, their decisions make sense in the context of their busy lives. Their actions are pragmatic and rational, and reinforced through an obesogenic environment which includes the industrial food system; social norms; and working conditions. This environment is dynamically co-created through their individual actions.
This research concludes that influences at multiple scales create an obesogenic environment that affects the vast majority Canadians. Of particular importance are: the structure of the industrial food system (ubiquitous availability of calorie-dense processed, convenience foods); changing social norms regarding food; and working conditions. For this reason, public health interventions that focus only on education to improve lifestyle behaviours will do little to improve health outcomes, including overweight and obesity. Strategies need to focus on structural influences such as improving: food environments; social norms regarding gender, families and food; and working conditions.
