Epidemic Proportions: Obesity and Place

How where we live is making us obese

Published on October 16, 2012by Elaine Meyer

Mayor Michael Bloomberg’s proposal this summer to ban large sodas set off a national debate about the level of government involvement in combating America’s ever-widening obesity epidemic.

Against charges that government regulation of unhealthy food and drink reeks of paternalism, a growing chorus of voices in the public health and medical community argue that obesity needs to be fought through changes at the societal and policy level, not just at the individual level.

“I see a role for personal responsibility, but I strongly believe that we have organized our society such that my will power is constantly being challenged,” says Dr. Andrew Rundle, an associate professor of epidemiology at Columbia’s Mailman School of Public Health, and the director of the university’s Built Environment and Health (BEH) Project, an interdisciplinary program that examines the effects of land use, public transit, and housing on physical activity, diet, and obesity.

Today, over one in three American adults is obese, and the rising obesity rate among children has led to predictions that younger generations may be the first in U.S. history to have shorter life spans than their parents.

In May, the Institute of Medicine (IOM) released a report that disputed the idea that the obesity epidemic can be fixed primarily by telling individuals to modify their behavior.

“People have heard the advice to eat less and move more for years, and during that time a large number of Americans have become obese,” Dr. Shiriki Kumanyika, a member of the IOM, told Reuters recently. “That advice will never be out of date. But when you see the increase in obesity you ask, what changed? And the answer is the environment. The average person cannot maintain a healthy weight in this obesity-promoting environment.”

Most funded research has focused on how individual behavior choices contribute to obesity. According to Drs. Anthony Robbins and Marion Nestle such studies “do little but offer cover to an industry seeking to downplay its own responsibility.”

However, a group of academics has for over a decade championed the perspective articulated in the IOM report. They contend that the American landscape of fast food restaurants, convenience stores, strip malls, cul-de-sacs, drive-thrus, and highways have produced widespread obesity.

One of the leaders in this field, Dr. Richard Jackson, chair of environmental sciences department at the University of California Los Angeles’ School of Public Health, says that eleven years ago, his views were considered so controversial he was nearly fired.

Today, they are at the center of the PBS television series “Designing Healthy Communities,” which came out earlier this year.

“Societal changes over decades have dramatically reduced the need for physical activity in daily life while creating ubiquitous barriers to physical activity,” says a recent paper by Dr. James Sallis, another researcher in the field, who is a professor of family and preventive medicine and head of Active Living Research, a Robert Wood Johnson Foundation program based at the University of California-San Diego.

One manifestation is the decline of walking. From 1977 to 1995, the number of walking trips by adults decreased 32 percent, with a similar decline for children.

A neighborhood’s “walkability”—the degree to which it promotes walking, based on measures such as density, proximity to parks and trails, and distance to public transportation—is associated with greater physical activity, according to research from Dr. Rundle’s group, BEH.

Lack of availability of healthy foods, particularly in low income neighborhoods is also a problem. In New York City, BEH found in a 2009 study that obesity rates are lower in neighborhoods where healthy food is more accessible.

Industry, public officials and even some of the researchers in this field say that it is difficult to point to the mechanism by which the environment contributes to a more obese population.

Because of the many factors that contribute to health, it is difficult to design a study that identifies a clear cause and effect relationship between obesity and the surrounding environment. Most studies are cross-sectional, meaning they take a snapshot of obesity rates at one point in time rather than over time.

In a cross-sectional study for instance, it is not clear whether living near a park encourages people to exercise to lose weight or whether already weight-conscious people, like runners, concertedly seek out housing near a park. This is because researchers do not have access to data that would allow them to see if people of healthy weight had been obese or overweight before living near the park.

“If more runners move to areas near a park, the park has not necessarily caused more people to run,” says Dr. Gina Lovasi, an assistant professor of epidemiology at Columbia’s Mailman School of Public Health and an investigator at BEH.

Although it may take years to understand this relationship, many experts who study the built environment say interventions are important now. They point to past public health campaigns that have taken root before the cause of an epidemic was completely understood, such as anti-tobacco efforts in the 1960s and 1970s.

The IOM report recommends that society make changes, including modifying zoning laws to promote physical activity; introducing a soda tax; and ending subsidies that give incentives to farmers to grow too much grain, which some associate with creating cheaply available calories.

Efforts to “retrofit suburbia” are already taking place in some communities.

But these changes face an uphill battle because they often target powerful interest groups, including real estate developers, agribusiness and soft drink companies.

In a sign of what may be to come, the soft-drink industry on October 12 filed suit against Mayor Bloomberg contending that the soda ban “violate[es] one of the core principles of democratic government and ignor[es] the right of the people of New York City to make their own choices.”

The question is whether courts, legislatures, and ultimately the public will agree.

Edited by Dana March. Additional research by Joshua Brooks.