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Johns Hopkins: Using Computer-Simulation Modeling to Design and Test Obesity Prevention and Control Policies

The Global Obesity Prevention Center (GOPC) at Johns Hopkins Bloomberg School of Public Health is tackling obesity prevention and control with a systems approach. The food environment, policy, economics, social influences, behavior and physiology all make up the complex system of obesity. GOPC’s executive director, Dr. Bruce Y. Lee, recognizes that sustainable obesity prevention and control interventions and policies must fully capture and characterize these complex factors and interactions in a given community, city or region.

Breaking New Ground

Using its Virtual Population Obesity Prevention (VPOP) laboratories, the GOPC develops computational simulation models of communities, cities and regions that allow decision makers (e.g., policy makers, funders, public health officials, school officials and business professionals) to better understand and address the various systems contributing to obesity and affecting diet, physical activity and metabolism. The virtual laboratories can save considerable time, effort and resources by allowing decision makers to test hypothetical interventions and policies through computer modeling before actual implementation (think “SimCity” for obesity prevention and control).

To date, the GOPC has developed VPOP simulation models of Baltimore, New York City, Mexico CityNew Orleans, PhiladelphiaSan Francisco and Washington D.C. Each model includes geospatially explicit virtual representations of each person and relevant locations (e.g., households, schools, physical activity sites such as gyms, parks and recreation centers, and food sources such as grocery stores, fast food restaurants, corner stores and sit-down restaurants).

In the virtual communities, people go about their routine daily activities and make decisions about diet and physical activity. The virtual residents, like real people, can gain and lose weight depending on how many calories they consume and expend.

VPOP models have helped answer the following questions:

What is the economic, epidemiologic and clinical impact of increasing the physical activity of children?

Dr. Lee and his colleagues used their VPOP platform to represent the current population of U.S. children and to show how changes in levels of physical activity could improve their health and reduce direct and indirect healthcare costs over their lifetime. “Physical activity not only makes kids feel better and helps them develop healthy habits, it’s also good for the nation’s bottom line,” says Dr. Lee. The findings, published in Health Affairs suggest that increasing the number of elementary school children in the United States who participate in 25 minutes of physical activity three times a week from 32 percent to 50 percent would save over $21 billion in medical costs and lost wages over the course of their lifetimes.

What is the impact of crime on African American women’s physical activity and obesity?

The GOPC and the National Heart, Lung, and Blood Institute (NHLBI) used VPOP software to explore how reducing crime levels in high-risk urban communities can increase physical activity levels and significantly reduce obesity prevalence among African American women. The model included virtual representations of households, physical activity and crime locations and African American women in DC. Each simulated day, each female agent decided if, where and how much she would exercise. In the model, crime reduced the accessibility of physical activity locations in DC, which then reduced the likelihood of an agent exercising. The study, published in Obesity, suggests that policies to reduce neighborhood crime could boost exercise levels and significantly cut obesity rates.

How can increasing the number of trained coaches impact youth participation rates in physical activity?

Laureus Sport for Good USA (Laureus USA) prioritized support for coaches across New Orleans to promote sustainable physical activity opportunities for youth. However, observing and quantifying the community and health impact of increasing coaches through long-term studies often requires substantial time, effort and resources. Laureus USA utilized GOPC’s VPOP platform to develop a virtual city of Orleans Parish to explore the impact of prioritizing support for trained coaches. The study found that even relatively small increases in the number of coaches could have significant positive impacts on youth physical activity and obesity prevalence.

How can the implementation of sugar-sweetened beverage (SSB) warning labels impact obesity prevalence?

The GOPC and Pittsburgh Supercomputing Center (PSC) created a version of VPOP to show the impact of implementing warning labels in stores that sell sugary drinks in Baltimore, Philadelphia and San Francisco. The virtual warning labels used in the model contained messaging that notes how added sugar contributes to tooth decay, obesity and diabetes. Results from the model found that warning labels in locations that sell sugary drinks, including grocery and corner stores, reduced both obesity and overweight prevalence in all three cities. Results from this study could help policymakers and other decision makers understand the potential effects of implementing sugary-drink warning labels.