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Sloth: Is Your City Making You Fat?

Sloth: Is Your City Making You Fat?
Reported by
Linda Lee

Posted May 02, 2013


There are many well-known reasons for weight gain, including unhealthy diets and sedentary lifestyles, as well as certain diseases and medications. A perhaps more subtle factor, which is discussed less but affects most Americans, is urban planning: the design, infrastructure, and resources of our built environment. To grasp how urban planning affects health, consider the profusion of sprawling suburbs with amenities that cannot be reached by walking or cycling, where driving is the primary mode of transportation; consider the densely populated urban centers with few, often overcrowded parks and limited access to outdoor activities and athletics.

As part of the Academy's Science and the Seven Deadly Sins series, the Sackler Institute for Nutrition Science and Science & the City presented a panel discussion titled Sloth: Is Your City Making You Fat? on March 13, 2013, to discuss how designing and building a better urban environment could improve city residents' health and reduce obesity. Author Tom Vanderbilt, the panel moderator, began by noting that New York City scores very high in walkability, a measure that includes the ease, safety, and convenience of walking. In fact, New York and San Francisco are the most walk-friendly cities in the U.S. according to He stressed that walkability impacts general measures of health and well-being, not just obesity. For example, the risk of crash injuries and environment-related health problems such as asthma are intertwined with urban design. Intriguingly, urban design can also impact social relationships, which are linked with general health; Vanderbilt reported a study in San Francisco that found an inverse correlation between car traffic on a street and the number of social relationships of a resident of that street.

Urban policy and planning can improve the health impact of the built environment. According to Kaid Benfield, director of sustainable communities at the Natural Resources Defense Council, there has been a shift in urban design in recent decades away from suburban sprawl toward compact, walkable communities. Indeed, improving walkability has become a policy priority in many locales, driven by resident demand. This shift is due in large part to changing demographics—more childless singles, childless couples, and older adults. These groups generally prefer urban living and walkable neighborhoods.

Exploring how to improve New York City's walkability, FAST NYC co-founder Hunter Reed recommended interventions focused on accessibility, such as building sidewalk infrastructure, and stressed the importance of using new technology to maintain the city's high walkability. For example, he suggested that autonomous driving, a technology Google is developing, would make streets safer by reducing accidents. Mariela Alfonzo from the Polytechnic Institute of New York University described cities as dynamic places where frequent redevelopment provides opportunities to address and improve urban design. She noted that architecture with visually interesting features can encourage walking. She also pointed out that although New York City has high walkability scores, there is significant inequality among its boroughs: Manhattan scores very high but the outer areas of other boroughs are hampered by wide streets, inconvenient or too-few crossings, and a lack of pedestrian safety features.

How can policy makers encourage walking? One option is to build more walkable destinations. Benfield mentioned a study that found a 25% higher rate of walking among residents with access to shops and other recreational destinations. Public transportation is also important because it reduces car use and involves walking at the beginning and end of each trip. One study found that the installment of a commuter rail line led to weight loss among community residents. According to Benfield, intersection density—the number of intersections per square mile—is the best indicator of the walkability of a neighborhood; and intuitively, smaller blocks are more convenient and easier to walk. High intersection density can be built into new neighborhoods, where street grid planning is making a comeback, and incorporated into older neighborhoods that are retrofitted. As Vanderbilt noted, improvements will not be successful if residents resist redevelopment or do not use new amenities. Alfonzo stated that residents’ preferences are changing: an increasing focus on quality of life and environmental issues has raised demand for walkable neighborhoods.

Reed described the health benefits of walking as proportional to its duration and intensity. Benfield noted research supporting the advantages of simply walking more: controlling for demographic factors, residents of walkable neighborhoods weigh approximately 10 pounds less than residents of less walkable areas, he said; thus, increased walking, not necessarily at an intense aerobic pace, can create measurable health benefits.

The panelists also discussed impacts of walkability that are not health related, particularly the relationship between walkability and economic status. Vanderbilt cited research that shows that residents of less walkable areas tend to be less affluent and to have a lower level of education than their counterparts in more walkable neighborhoods. The directions of any cause–effect relationships in these correlations are unclear. However, Alfonzo said that it is important to consider socioeconomic factors when introducing new interventions or policies, in order to improve walkability without changing demographics or promoting gentrification. Thus, policy makers should focus on maintaining accessibility for low-income residents through affordable housing and should collaborate with local organizations to create solutions that are appropriate for the community.

Although the relationship between walkability and economic status is not always simple (many wealthy suburbs are not especially walkable), improved walkability has been linked to higher real estate values. Benfield discussed research demonstrating that home values are higher in neighborhoods with high walk scores—a measure of walkability that is based primarily on the number and distance to shops and other amenities within walking distance (<1 mile). Alfonzo pointed to a study that found a statistically significant relationship between State of Place and economic value for both commercial and residential property in the Washington, DC metro region. State of Place is a walkability rating and diagnostic tool created by Alfonzo, based on built-environment features that are empirically linked to walking: density, proximity to destinations, connectivity, parks and public spaces, form, physical activity facilities, pedestrian amenities, traffic safety, crime safety, and aesthetics.

Benfield emphasized the importance of creating peaceful spaces within cities but noted that it can be difficult to find a balance between stimulation and calm in the urban environment. He suggested building small neighborhood parks and courtyards in areas that need to maintain an urban streetscape. Highway walls and parks spaces sunken below street level can provide isolation from traffic noise. Green infrastructure that includes features such as greenery-lined roads and incorporates natural landscape features can create natural spaces while fulfilling functional purposes, such as managing storm-water runoff and flooding. Designing parks and other spaces for contemplation and recreation complements efforts to increase street walkability and can enhance residents' well-being by improving mental health and community cohesiveness

Alfonzo pointed out that neighborhood parks are community gathering spaces that can be especially important in poor areas. She described residents without access to affordable transportation as figuratively "locked-in," and thus confined to their local neighborhood. Parks provide outdoor recreation space and safe playgrounds. Reed mentioned that landscaping choices can significantly impact park use. For example, Riverside Park in New York City has turf and is accessible year-round, but Central Park does not, so its large fields are inaccessible during inclement weather, about five months of the year. He suggested that parks should increase the use of greenery to insulate park sections and should install turf in high-use fields to improve accessibility.

Athletic organizations and facilities can promote health but are often scarce and very expensive in crowded, space-constrained urban areas. Reed noted that this lack of resources can be particularly detrimental for children living in low-income inner-city areas where schools are poorly financed and do not always have sports programs. The high rate of obesity among inner-city children highlights the need for athletic facilities, especially in areas that lack neighborhood parks. There is increasing recognition of this issue, and New York and other cities have established programs to bring mentoring and sports options to children in poor neighborhoods.

Cycling is another active transport that is often promoted in cities, despite some controversy. The New York City bike share program, which is expected to become available in the summer of 2013, has both proponents and opponents. Because cycling programs require the addition of bike lanes to roadways, there is often conflict that pits the interests of cyclists against those of drivers; successful cycling programs must address the concerns of both groups and focus on improving the safety of a shared roadway. Benfield argued that the view held by some proponents of urbanity—that car drivers are the enemy—should be discouraged. The majority of Americans own and drive cars and will continue to do so for the foreseeable future, so bike lanes should be planned thoughtfully and should not intrude on driving lanes. The panelists agreed that cycling facilities and bike share programs are positive developments for the well-being of urban residents.

Urban design initiatives that create walkability—with walkable destinations, sidewalks, and features such as high intersection density, safety, walking comfort, and visual interest—will shift the design-focus of our environment to promote health. Amenities such as cycling lanes, green spaces, park access, and athletic venues will improve the accessibility of health and fitness resources for community residents. Planners should be mindful of the diversity and unique characteristics of individual neighborhoods and should tailor interventions to fit these parameters. In light of the epidemic rates of obesity and obesity-related diseases, we need to address "sloth"—Why not start at our doorsteps?

Use the tab above to find multimedia from this event.

Presentations available from:
Moderator: Tom Vanderbilt (Author)
Mariela Alfonzo, PhD (Polytechnic Institute at New York University)
Kaid Benfield (Natural Resources Defense Council)
Hunter Reed (FAST NYC)

Presented by

  • Science and the City
  • The Sackler Institute for Nutrition Science

Sloth: Is Your City Making You Fat?

Moderator: Tom Vanderbilt


Journal Articles and Reports

Doyle S, Kelly-Schwartz A, Schlossberg M, Stockard J. Active community environments and health: the relationship of walkable and safe communities to individual health. J Am Plann Assoc. 2006;72(1):19-31.

Frank LD, Sallis JF, Conway TL, et al. Many pathways from land use to health: associations between neighborhood walkability and active transportation, body mass index, and air quality. J Am Plann Assoc. 2006;72(1):75-87.

Giles-Corti B, Bull F, Knuiman M, et al. The influence of urban design on neighborhood walking following residential relocation: longitudinal results from the RESIDE study. Soc Sci Med. 2013;77:20-30.

Godbey G, Mowen A. The benefits of physical activity provided by park and recreation services: the scientific evidence. Research Series. National Recreation and Park Association. 2010.

Orsega-Smith E, Mowen AJ, Payne LL, Godbey G. The interaction of stress and park use on psycho-physiological health in older adults. J Leis Res. 2004;36(2):232-256.

Maizlish N, Woodcock J, Co S, Ostro B, Fanai A, Fairley D. Health cobenefits and transportation-related reductions in greenhouse gas emissions in the San Francisco Bay area. Am J Public Health. 2013;103(4):703-9.

Pikora TJ, Giles-Corti B, Knuiman MW, Bull FC, Jamrozik K, Donovan RJ. Neighborhood environmental factors correlated with walking near home: Using SPACES. Med Sci Sports Exerc. 2006;38(4):708-14.

Saelens BE, Sallis JF, Frank LD. Environmental correlates of walking and cycling: findings from the transportation, urban design, and planning literatures. Ann Behav Med. Spring 2003;25(2):80-91.

Saelens BE, Sallis JF, Frank LD, et al. Obesogenic neighborhood environments, child and parent obesity: the Neighborhood Impact on Kids study. Am J Prev Med. 2012;42(5):e57-64.

Smith KR, Brown BB, Yamada I, Kowaleski-Jones L, Zick CD, Fan JX. Walkability and body mass index density, design, and new diversity measures. Am J Prev Med. 2008;35(3):237-44.

van Lenthe FJ, Brug J, Mackenbach JP. Neighborhood inequalities in physical inactivity: the role of neighborhood attractiveness, proximity to local facilities and safety in the Netherlands. Soc Sci Med. 2005;60(4):763-75.

Websites and Videos

TED: Ideas Worth Spreading. Ellen Dunham-Jones: Retrofitting Suburbia. 2010.

TED: Ideas Worth Spreading. TEDx. Dan Burden: Creating Livable Communities. 2011.

The City 2.0. Jason Sweeney: Crowdsourcing the Quiet. 2012.

Walkable and Livable Communities Institute


Tom Vanderbilt


Tom Vanderbilt writes for publications including Wired, Outside, The London Review of Books, The Financial Times, The Wall Street Journal, The Wilson Quarterly, Artforum, Rolling Stone, The New York Times Magazine, and Popular Science. He is contributing editor to Artforum and the design magazines Print and I.D., contributing writer of the blog Design Observer, and a columnist for Slate Magazine. His most recent book is the New York Times bestseller Traffic: Why We Drive the Way We Do (and What It Says About Us). He is also the author of Survival City: Adventures Among the Ruins of Atomic America and The Sneaker Book. He blogs at and tweets at @tomvanderbilt.


Mariela Alfonzo, PhD

Polytechnic Institute at New York University
website | publications

Mariela Alfonzo is the founder of State of Place, a place rating and walkability diagnostic tool tied to economic value; president of Urban Imprint, an urban design research and consulting firm; and a research fellow and adjunct professor at NYU–Polytechnic Institute, where she is focusing on the links between the built environment and obesity in rapidly urbanizing Chinese cities. For over a decade, Alfonzo studied the relationship between the built environment and behavior, focusing on walkability and sustainability within the context of neighborhood revitalization. Her research and consulting work has included walkability evaluations, extensive work on walkability metrics, suburban retrofitting, and the triple bottom line of urban design, all with the goal of producing evidence-based design and policies. She holds a PhD in urban and regional planning, with an emphasis on urban design and behavior, and a Master's degree in urban planning from the University of California, Irvine. She tweets at @stateofplaceorg.

Kaid Benfield

Natural Resources Defense Council
e-mail | website

Kaid Benfield is director of sustainable communities at the Natural Resources Defense Council in Washington, DC. He leads NRDC's activities pursuing solutions to environmental challenges where Americans live, work, and play. Benfield teaches regional planning and sustainable development practices at the George Washington University School of Law. He co-founded LEED for Neighborhood Development, a national process for defining and certifying smart, green land development under the auspices of the U.S. Green Building Council. He is a founder and board member of Smart Growth America, a nationwide coalition working on revitalizing cities, building better neighborhoods, and stopping the spread of suburban sprawl. Benfield is the author of Once There Were Greenfields, Smart Growth in a Changing World, and Solving Sprawl. He writes for The Atlantic Cities, Huffington Post, Sustainable Cities, Better Cities and Towns, and the NRDC website. His forthcoming book is People Habitat: 20 Ideas that Change the Way We Think About Cities.

Hunter Reed


Hunter Reed is president and co-founder of FAST NYC, a nonprofit working to respond to the accelerating rate of obesity and type 2 diabetes among New York City's children, as well as to address the lack of nutrition education and physical activity programs in public schools. FAST NYC helps schools to develop, implement, and establish healthy eating and physical activity policies and practices through nutrition, exercise, and sports programs that are tailored to fit each school's individual needs. FAST NYC uses a coordinated approach, working closely with each school's principal and parent association to help schools to encourage, inspire, and support healthy eating and regular physical activity.

Linda Lee

Linda Lee holds a PhD in neurobiology and behavior from Columbia University. She studied a type of protein modification (SUMOylation) and how it is involved in the signaling pathways that lead to learning and memory. Her work focused on how this modification process is altered in Alzheimer’s disease. She is currently a postdoctoral fellow at Columbia University.


Presented by

  • Science and the City
  • The Sackler Institute for Nutrition Science