Environmental influences on food choice, physical activity and energy balance
Introduction
There are major gaps in our understanding of the way shifts in the physical and social environments affect changes in dietary intake, physical activity patterns and weight change. Nonetheless we have made major progress in the past decade to understand some aspects of this complex relationship. Much of this evidence suggests that environmental factors bear significant influence on diet, physical activity, and obesity [1], [2], [3]. Further, extensive research is either underway or planned to continue to push forward knowledge in this area. The environment is conceptualized very differently in the social and biological literature. For this paper, environment is defined as the macro- and community-level factors, including physical, legal, and policy factors that influence household and individual decisions. Thus, environment is conceived as the external context in which household and individual decisions are made.
Much of the literature on environmental correlates of diet, activity, and obesity has focused on the built environment. The built environment is defined as a multidimensional concept, broadly including patterns of human activity at various scales of geography within the physical environment. Handy et al. [4] state that the built environment includes: 1) “urban design, the design of a city and its physical elements; 2) land use, location and density of residential, commercial, industrial, forest, and others; and 3) transportation system, physical infrastructure of roads, sidewalks, bike paths, and others.” In this paper we will present data on these built environment factors as well as macro- and community-level factors that influence diet, physical activity, and obesity.
There are a number of key points to keep in mind. Dietary patterns have shifted remarkably across the globe over the past several decades. The foods we eat, the location of eating, the number of eating events, and even the composition of the persons at each eating event have changed. Behind these changes lie vast shifts in food production, processing, and distribution systems as well as food shopping and eating options. Similarly, the ways we move at work [be it market work or home production], shopping, leisure, and travel have shifted markedly over the past several decades. The changes in our built environment and the technology of work are most important in explaining many of these shifts. These changes have led to equally marked shifts in energy imbalance and obesity patterns across the globe. Elsewhere we summarize some of these points as they relate to adults and children [5], [6].
This paper is mainly a review of what we know about dietary and physical activity patterns and trends and their environmental determinants and correlates. In addition, we include built environment factors plus a wider range of environment factors including economic, legal, and policy factors. We present two case studies in a nationally representative cohort of US adolescents. These case studies illustrate the potential importance of key environment factors in shaping physical activity and obesity, and further how these environment factors may impact health disparities in the US population. The focus is on higher income countries as most of the research and programmatic activity in this area that has been studied and evaluated comes from the US, Europe and Australia.
Section snippets
Dominant US dietary trends
Extant knowledge appears to show that total caloric intake is increasing among all race, age, gender and socioeconomic groups (though there is no way to address some methodological differences in survey methods between the 1980s and the 1990s). These calories are more frequently coming from energy-dense, nutrient poor snacks [1], [7], [8], [9] at a greater frequency throughout the day [10], [11]. Furthermore, a greater number of meals are being consumed away from home [9], [12], [13], [14],
Physical environment/context
Environments may restrict a range of physical activity behaviors by promoting or discouraging physical activity through factors such as, access to safe recreation, accessibility of recreation facilities, and transit options. The physical activity literature is just beginning work on the conceptualization of environmental variables; thus there is limited understanding of the influence of such factors on physical activity. Early research has examined environmental determinants such as community
Case study one [109]
The objective of the research conducted for the case study below is to examine environmental and sociodemographic determinants of leisure-time physical activity, with particular attention to participation in school Physical Education (PE), community recreation center use, and neighborhood crime. The implication is that these findings can point towards societal-level intervention strategies for increasing physical activity and decreasing inactivity among adolescents.
Case study two [175]
Case study two is also from our work with the National Longitudinal Study of Adolescent Health. In this nationally representative adolescent cohort, we use Geographic Information Systems (GIS) to assess the availability of recreational facilities in the neighborhoods of our sample. We explore the distribution of these facilities by population characteristics to assess the geographic and social distribution of physical activity facilities and how disparity in access might underlie
Conclusions
A call for a greater focus on built environmental factors is common to most recent examinations of the obesity and inactivity epidemic and includes factors such as urban design, transport, and policy to promote physical activity [136], [137], [176]. Several research agendas for work on the built environment and health have been proposed in recent years [177], [178], [179]. A wealth of research questions and methodological issues have been elucidated by these authors with a shared emphasis on
Contribution of environmental factors to physical activity patterns
Results from the case studies in the nationally representative cohort of adolescents suggest that environmental factors play a major role in shaping physical activity and overweight. Our work shows important associations between modifiable environmental factors, such as participation in PE and community recreation programs with activity patterns of adolescents. Despite the marked and significant impact of participation in physical education programs on physical activity patterns of US
Inequality in access to the built environment and its effects
Our work with availability of physical activity facilities across over 20,000 adolescents and 19% of all US census block groups provides the first empirical evidence that all major categories of physical activity-related resources are inequitably distributed, with high minority, low educated neighborhoods at a strong disadvantage. Importantly, the inequitable distribution of facilities is apparent across all major categories of facilities including those facilities that we consider to be more
Summary
Taken together, our national work suggests that environmental factors play an important role in shaping obesity-related behaviors, particularly physical activity. This is a field in its infancy. While we clearly do not have the empirical base to assert that wide-spread changes in the built environment will lead to population-wide increases in physical activity, there is building evidence of the important relationship between environmental correlates and physical activity behavior. Innovative
Acknowledgments
Major funding for this study comes from the National Institutes of Health: NICHD (R01-HD39183-01, R01 HD041375-01and K01 HD044263-01). Additional funding comes from NIH (R01-HD39183-01, and DK56350), the Centers for Disease Control and Prevention (CDC SIP 5-00), and the Carolina Population Center. The authors would like to thank Ms. Frances Dancy for her helpful administrative assistance. This research uses data from Add Health, a program project designed by J. Richard Udry, Peter S. Bearman,
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