Tuesday, July 12, 2011

Some musings on sustainability and obesity: focusing on BOTH physical activity & diet needed

There is no disputing that diet and physical inactivity are contributors to the obesity epidemic. A recent debate involving Drs Yoni Freedhoff and Bob Ross showed that both are important (I don’t think there was consensus in the audience as to who won). What I want to highlight in this post is that, from a sustainability perspective (see my previous post for a definition), it is a moot point to argue over the relative importance of each.

Our food system has changed dramatically over the last few decades. We can get tasty, energy dense, often nutrient-poor foods anywhere, for very little money. And we’re constantly bombarded with advertisements to buy and eat these foods. What’s more is that we have almost completely engineered physical activity out of our daily life. For instance, most jobs nowadays require sitting for 8 hours (I am sitting as I write this), escalators and elevators do the climbing for us and are easily accessible, and we live far from where we work, play, or go to school so often must rely on the car, which involves more sitting.

I think there is a consensus developing among obesity researchers and health professionals that obesity (or diabetes or other related diseases) is not entirely the fault of the individual. In my opinion, unhealthy behaviours are a natural response to our “obesogenic” environment, which increase a person’s risk of developing obesity. So then why do we expect that prevention or treatment efforts targeted at the individual will be effective and maintained over the long-term? To fix our deranged food system and culture of sitting requires interventions at higher levels of social organization, including changes stemming from the local community, municipal, provincial, and national governments, as well as the global community.

In the last 10 years there has been a boom the number of scientific studies examining how our environments, beyond the household, are associated with obesity. The majority of these studies have been observational, with a cross-sectional design, and have looked at things like how street infrastructure, fast food restaurant density, and socioeconomic-level of residential neighbourhoods relate to obesity among adults.  Children have been less studied in this regard, as well as other types of environmental exposures, such as social interactions, and other types of areas, such as those around workplaces and schools (since these are likely not in one's residential neighbourhood).  Perhaps because of the complexity involved, even fewer studies have examined how specific policies and programs may influence physical activity, diet, and obesity at higher levels of social organization (you can find an example here).    

Certainly more studies are needed given the weaknesses in the current literature, as well as the dearth of information in some areas. But I would like to put forward another argument.  Increasing the “walkability” and “liveability” of our shared spaces - *may* decrease obesity but will likely help to decrease green house gas emissions. Making it easier for us to get and cook wholesome foods (namely fruits and veggies) that are free of pesticides, antibiotics, and other chemicals, and harder to get meat, as well as processed foods *could* decrease obesity, but could also help to reduce land degradation, pollution of our water sources, and climate change. All of these things are good for our health in ways other than on our waistline.       

My argument is that if there is a focus on sustainability, which these changes imply, population and environmental health should follow.  We need to focus on BOTH the diet and physical activity side in order to not only combat obesity, but a myriad of environmental problems and related health ailments like diabetes and asthma.  These changes are complex, don’t happen overnight, and may bring with them a whole set of new problems (the potential problem of denser living leading to a decrease in indoor air quality immediately comes to mind as an example). 

Nonetheless, I think we need to move towards rigorously implementing and evaluating interventions that increase sustainability – looking to see if they a) improve the environment, b) reduce obesity, or improve lifestyle behaviours, and c) that they do not negatively impact health in other ways (a post for another day).

Feng J, Glass TA, Curriero FC, Stewart WF, & Schwartz BS (2010). The built environment and obesity: a systematic review of the epidemiologic evidence. Health & place, 16 (2), 175-90 PMID: 19880341

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