Date of Award
Doctor of Philosophy (PhD)
Civil and Environmental Engineering
Since the 1970s, the percentage of the US population that is overweight and obese has increased significantly, with nearly 70% of American adults now overweight or obese (National Center for Health Statistics, 2013). The American Medical Association officially recognized obesity as a disease (American Medical Association, 2013) that afflicts approximately one out of every three adults in the US (National Center for Health Statistics, 2013). While the health implications of being overweight or obese are well established, the environmental impacts have not received equal attention. In light of this inattention, this dissertation analyzes the effects of the overweight and obese population on energy use, water withdrawals, greenhouse gas (GHG) emissions, and fuel costs through the US food supply system and transportation system. The first empirical chapter investigates the impacts of current US food consumption on energy use, water withdrawals, and GHG emissions. The purpose of this analysis is twofold: first, two top-down approaches are used to establish a range of life-cycle industrial energy use, water withdrawals, and GHG emissions in the US food supply system that are attributed to total food consumed by the US adult population. The two methods utilized are 1) economic input-output life-cycle assessment (EIO-LCA) and 2) process-based analysis. Second, the additional industrial energy use, water withdrawals, and GHG emissions required to support the extra Caloric intake of the US overweight and obese adult population are estimated. Extra Caloric intake estimates are developed using anthropometric data from the Centers for Disease Control (CDC) National Health and Nutrition Examination Survey. In 2012, 6.1-6.2 million TJ of cumulative energy use, 100-105 billion m3 of water withdrawals, and 600 million metric tons (MMT) CO2-eq were needed to provide food to the US adult population. Furthermore, 8-10% of total Caloric intake of adults were extra Calories consumed from overeating for overweight and obese adults. Providing these additional Calories resulted in 440,000-610,000 TJ of energy use, 7-10 billion m3 of water withdrawals, and 43-59 MMT CO2-eq. The second empirical chapter uses a bottom-up approach to measure the changes in energy use, water withdrawals, and GHG emissions associated with shifting from current US food consumption patterns to three dietary scenarios, which are based, in part, on the 2010 USDA Dietary Guidelines (US Department of Agriculture and US Department of Health and Human Services 2010). Amidst the current overweight and obesity epidemic in the US, the Dietary Guidelines provide food and beverage recommendations that are intended to help individuals achieve and maintain healthy weight. The three dietary scenarios examined include 1) reducing Caloric intake levels to achieve “normal” weight without shifting food mix, 2) switching current food mix to USDA recommended food patterns, without reducing Caloric intake, and 3) reducing Caloric intake levels and shifting current food mix to USDA recommended food patterns, which support healthy weight. This analysis finds that shifting from the current US diet to dietary Scenario 1, decreases energy use, water withdrawals, and GHG emissions by around 8.5%, while shifting to dietary Scenario 2 increases energy use by 48%, water withdrawals by 22%, and GHG emissions by 13%. Shifting to dietary Scenario 3, which accounts for both reduced Caloric intake and a shift to the USDA recommended food mix increases energy use by 39%, water withdrawals by 13%, and GHG emissions by 6%. The third empirical chapter analyzes the transportation industry to determine the amount of additional fuel use, GHG emissions, and fuel costs that are attributed to excess passenger weight in light-duty vehicles, transit vehicles, and passenger aircraft in the US from 1970 to 2010. Using driving and passenger information in the US and historical anthropometric data, it is estimated that since 1970 over 205 billion additional liters of fuel were consumed to support the extra weight of the American population. This is equivalent to 1.1% of total fuel use for transportation systems in the United States. Also, excess passenger weight results in an extra 503 MMT CO2-eq and $103 billion of additional fuel cost over the last four decades. If overweight and obesity rates continue to increase at its current pace, cumulative excess fuel use could increase by 460 billion liters over the next 50 years, resulting in an extra 1.1 billion metric tons CO2-eq and $200 billion of additional fuel costs by the year 2060.
Tom, Michelle S., "Impacts of the Overweight and Obese on the US Food Supply and Transportation Systems" (2015). Dissertations. 603.