Are climate change and obesity linked?
Are Obesity and Climate Change Connected?
Obesity and climate change are two of the most pressing modern challenges.1 On the surface, there appears to be no connection between them, beyond their coexistence as major threats to global health and sustainability.
However, recent research suggests a causal bidirectional link between obesity and climate change. Mounting evidence suggests that "current food production, transport, land use and urban design negatively impact both climate change and obesity outcomes."2 A recent article by Webb and Egger1 explores this connection.
Environmental Impact of Obesity
More than one-third of U.S. adults and approximately 17% of children and adolescents are obese.3 According to the World Health Organization, more than 1.4 billion adults worldwide were overweight in 2008. Over 200 million men and nearly 300 million women were obese. Overweight and obesity have nearly doubled since 1980 and have become the fifth largest cause of global mortality.4
The behaviors of obese individuals impact the environment.5,6 For example, many obese individuals are sedentary.7 Physical activity "is replaced by carbon-emitting, fossil fuel-powered transport."1
Obese individuals tend to have highly processed diets, which have a deleterious impact on the environment. For example, in comparison with the highly processed Westernized diets, more traditional plant-based diets are associated with fewer greenhouse gas (GHG) emissions.8
Populations with a higher percentage (more than 40%) of overweight individuals have a 19% increase in total energy expenditure associated with adiposity.1
A similar relationship exists between unhealthful diets and their impact on body weight. Plant-based diets are associated with lower rates of obesity.9 It follows that a "positive shift" toward a more plant-based diet should "not only reduce body weight but also contribute to reducing an individual's carbon footprint and hence, environmental impact."1
The Impact of Climate Change on Obesity
According to the Environmental Protection Agency (EPA), "global temperatures are rising, snow and rainfall patterns are shifting, and more extreme climate events—like heavy rainstorms and record high temperatures—are already affecting society and ecosystems."10
These changes "can be linked to the increase in greenhouse gases in the atmosphere, caused largely by people burning fossil fuels to generate electricity, heat and cool buildings, and power vehicles."10
Extreme climate events affect eating and shopping behaviors. One mechanism is "food insecurity"—a perception of "limited or uncertain access to adequate food," which can cause people to make unhealthful food-related decisions.11 The insecurity is realistic, since anthropogenic climate change leads to scarcity and higher food prices.11
In particular, this affects individuals in lower socioeconomic circumstances. After a climatic hazard event, households with limited pre-hazard resources are less able to effectively maintain food security.12 Typically, individuals with food insecurity are more likely to purchase lower-priced highly processed foods that contribute to obesity.11
Webb and Egger note that public health campaigns "have not translated into common practice." The authors suggest that the reason for this "disconnect" is "rapid changes to the macro- and microenvironments through economic development, which overwhelms these health messages." The "obesogenic" environment continues to "hold the balance of power" in the war against obesity.
Interventions often target corporations,13 forcing them to be responsible and find "greener," more environmentally friendly alternatives. But interventions targeting corporations are insufficient, since 40% to 50% of GHG emissions come from individuals and households.14
Personal Carbon Trading (PCT) is a system that engages individuals in reducing emissions,15 and emission-reducing behaviors also lead to obesity-reducing behaviors. PCT is designed to "entice individuals to have more responsibility for their own carbon-related... and... health-related behavior"1 by giving individuals a personal carbon allowance.