Obesity and Climate Change

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Mounting evidence suggests that “current food production, transport, land use and urban design negatively impact both climate change and obesity outcomes.”

Obesity and climate change are two of the most pressing modern challenges. 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. A recent article by Webb and Egger explores this connection.

Let’s examine this:

  • Environmental Impact of Obesity

More than one-third of U.S. adults and approximately 17% of children and adolescents are obese. 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.. The behaviors of obese individuals impact the environment. For example, many obese individuals are sedentary.

Physical activity “is replaced by carbon-emitting, fossil fuel-powered transport.”

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. Populations with a higher percentage (more than 40%) of overweight individuals have a 19% increase in total energy expenditure associated with adiposity. A similar relationship exists between unhealthful diets and their impact on body weight. Plant-based diets are associated with lower rates of obesity. 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.”

  •  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.”  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.”

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. The insecurity is realistic, since anthropogenic climate change leads to scarcity and higher food prices. 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.  Typically, individuals with food insecurity are more likely to purchase lower-priced highly processed foods that contribute to obesity.

  • Seeking Solutions

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, forcing them to be responsible and find “greener,” more environmentally friendly alternatives. But interventions targeting corporations are insufficient, since 40-50% of GHG emissions come from individuals and households.

Personal Carbon Trading (PCT) is a system that engages individuals in reducing emissions, 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” by giving individuals a personal carbon allowance. This approach is being studied on Norfolk Island, a self-governing Australian protectorate. Researchers are investigating the possible impact of a PCT system on obesity-related behaviors.

After completing a baseline survey, residents received electronic “carbon cards,” which will record in real-time carbon-related behaviors (eg, use of fuel, power, and electricity and—in the second phase of the trial—food purchasing). Participants will be offered a hypothetical financial incentive or disincentive as a way of testing out the concept of a PCT. Data are currently being prepared for publication and results are pending.

Conclusion

Webb and Egger suggest that while PCT interventions is “unlikely” to independently solve population obesity, it does “have the potential to positively influence the macro environment, a key construct of the epidemiological triad.” They call for collaboration between health and environmental scientists to “communicate and support cross disciplinary initiatives and messages around climate change and obesity management.”

References

1. Webb GJ, Egger G. Obesity and climate change: can we link the two and can we deal with both together? Am J Lifestyle Med. September 12, 2013.

2. Skouteris H, Cox R, Huang T, et al. Promoting obesity prevention together with environmental sustainability. Health Promot Int. 2013 Feb 7. [Epub ahead of print]

3. Centers for Disease Control and Prevention. Overweight and obesity. (2013) Available at: http://www.cdc.gov/obesity/data/facts.html. Accessed: October 10, 2013.

4. World Health Organization. Obesity and overweight. (2013) Available at: http://www.who.int/mediacentre/factsheets/fs311/en/. Accessed: October 11, 2013.

5. Faergeman O. Climate change and preventive medicine. Eur J Cardiovasc Prev Rehabil. 2007;14(6):726-729.

6. Egger G, Pearson S, Pal S, Swinburn B. Dissecting obesogenic behaviours: the development and application of a test battery for targeting prescription for weight loss. Obesity Rev. 2007;8(6):481-486.

7. Endocrine Society. Obesity in America. (2013) Available at: http://obesityinamerica.org/understanding-obesity/. Accessed: October 11, 2013.

8. Eshel G. Martin PA. Diet, energy and global warming. Earth Interact.2006;1099:1-17.

9. Campbell TC, Campbell TM. The China Study: Startling Implications for Diet, Weight Loss, and Long-Term Health. Dallas, TX: BenBella Books, 2007.

10. United States Environmental Protection Agency (2012). Climate change indicators in the United States. Available at: http://www.epa.gov/climatechange/science/indicators/. Accessed: November 11, 2013.

11. Lake IR, Hooper L, Asmaa A, et al. Climate Change and Food Security: Health Impacts in Developed Countries. Environ Health Perspect. 2012;120(11):1520–1526.

12. Sherman M, Ford JD. Market engagement and food insecurity after a climatic hazard. Global Food Security. 2013;2(3): 144–155.

13. Leiserowitz A, Maibach E, Roser-Renouf C, et al. Global Warming’s Six Americas in September 2012. Yale University and George Mason University. New Haven, CT: Yale Project on Climate Change Communication. http://environment.yale.edu/climate-communication/files/Six-Americas-September-2012.pdf. Accessed August 5, 2013.

14. Intergovernmental Panel on Climate Change. Climate change: synthesis report. 2001. http://www.grida.no/publications/other/ipcc_tar/?src_/climate/ipcc_tar/vol4/english/.  Accessed October 11, 2013.

15. Fawcett T. Personal carbon trading: a policy ahead of its time? Energy Policy. 2010;38:6868-6876.

16. Norfolk Island Carbon Health Evaluation (NICHE) Study. Available at: www.niche.nlk.nf. Accessed: October 11, 2013.

___Submitted by Dr. Collin Ross___

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