Assessing the Evidence for Childhood Obesity Prevention Action Steps
The purpose of this appendix is to help the reader understand the nature of the evidence for the action steps.
To determine the most promising childhood obesity prevention actions for local governments, the committee reviewed numerous research articles from peer-reviewed published literature as well as reports from organizations that work with local governments on childhood obesity prevention. In order to be recommended, action steps were selected that local governments generally have the authority to carry out. In addition, they had to have a direct impact on children and they had to be actions that had been implemented by local governments or had been recommended by knowledgeable sources as actions for local governments. Finally, the recommended actions had to be ones that were likely to make positive contributions to the achievement of healthy eating and/or optimal physical activity based on research evidence or, where that was lacking or limited, have a logical connection with the achievement of healthier eating or increased physical activity.
The committee considered three categories of evidence, realizing that some actions had multiple types of evidence:
Intervention evidence: A few of the actions have been tested in randomized intervention studies. Randomized controlled trials are not feasible for many community efforts and while recognizing the value of this type of research,
the committee also realized the practical constraints that make it infeasible to examine the effectiveness of all types of actions in this way.
Observational evidence: A number of the action steps have been discussed in published studies that provide observations on how an action fared in one community or population, or examine associations of community characteristics with healthy eating, physical activity, or weight in a particular community or set of communities.
Limited evidence: Some action steps do not have direct research evidence. The selection of those actions was based on related evidence indicating that they are likely to have a positive effect on healthy eating and/or optimal physical activity. An example would be the action step to “create incentive programs to attract supermarkets and grocery stores to underserved neighborhoods.” Although there is no direct research evidence on the impact of incentive programs to attract supermarkets and grocery stores to these neighborhoods, there is observational evidence (cited in the rationale for Strategy 1: Retail Outlets) that neighborhood residents who have better access to supermarkets tend to have healthier diets and lower levels of obesity.
The 15 strategies recommended in the report are listed below, with a characterization under each one of the type of evidence supporting the action steps for that strategy. In addition, particular attention is paid to the types of evidence supporting each of the 12 action steps that the committee highlighted.
Actions For Healthy Eating
IMPROVE ACCESS TO AND CONSUMPTION OF HEALTHY, SAFE, AND AFFORDABLE FOODS
Strategy 1: Increase community access to healthy foods through supermarkets, grocery stores, and convenience/corner stores.
All of the action steps under this strategy have limited evidence. However, the action step to “create incentive programs to attract supermarkets and grocery stores to underserved neighborhoods” was highlighted by the committee as one of its 12 action steps for special consideration. As mentioned in the above example, there is observational evidence that neighborhood residents who have better access to supermarkets tend to have healthier diets and lower levels of obesity. This highlighted action step is likely to make positive contributions to the achievement of
healthier eating. It has the potential to reach a large population and several cities are in the process of implementing incentive programs. There is growing interest in the implementation of this action and increased research in this area would be useful.
Strategy 2: Improve the availability and identification of healthful foods in restaurants.
There is observational evidence supporting the action steps related to menu labeling. The committee’s highlighted action step under this strategy: “Require menu labeling in chain restaurants to provide consumers with calorie information on in-store menus and menu boards” is supported by observational evidence that calorie information may have a positive influence on food choices in a restaurant setting. This action step has the potential to reach a large segment of the population and is being implemented by a number of restaurant chains. There is a growing interest in the implementation of this action and increased research in this area would be very useful. On the other hand, there is limited evidence for the action step on offering incentives to restaurants that promote healthier options.
Strategy 3: Promote efforts to provide fruits and vegetables in a variety of settings, such as farmers’ markets, farm stands, mobile markets, community gardens, and youth-focused gardens.
There is intervention and/or observational evidence for all of the action steps under this strategy except one: “Develop community-based activities that link procurement of affordable healthy food with improving skills in purchasing and preparing food.” As with all of the steps with limited evidence, this categorization is a reflection of the lack of published research.
Strategy 4: Ensure that publicly run entities such as after-school programs, child care facilities, recreation centers, and local government worksites implement policies and practices to promote healthy foods and beverages and reduce or eliminate the availability of calorie-dense, nutrient-poor foods.
For this strategy, the action steps listed have limited evidence. The committee highlighted one action step under this strategy: “Mandate and implement strong nutrition standards for foods and beverages available in government-run or regulated after-school programs, recreation centers, parks, and child care facilities” because of the potential reach of such standard-setting and the feasibility of doing so in government-run and or regulated programs. There is growing interest
in the implementation of such an action, and more research on the effectiveness of nutrition standards in these settings would be helpful.
Strategy 5: Increase participation in federal, state, and local government nutrition assistance programs (e.g., WIC, school breakfast and lunch, the Child and Adult Care Food Program [CACFP], the Afterschool Snacks Program, the Summer Food Service Program, SNAP).
There is limited evidence on the action steps under this strategy. However, several observational studies show associations between nutrition program participation and lower BMI.
Strategy 6: Encourage breastfeeding and promote breastfeeding-friendly communities.
The majority of the action steps under this strategy have limited evidence. However, there is observational evidence supporting the action step: “Adopt practices in city and county hospitals that are consistent with the Baby-Friendly Hospital Initiative.”
Strategy 7: Increase access to free, safe drinking water in public places to encourage water consumption in place of sugar-sweetened beverages.
A recent study provides intervention evidence that supports the action steps under this strategy. The committee highlighted the action step: “Adopt building codes to require access to, and maintenance of, fresh drinking water fountains.” The research showed an increase in water consumption and a reduction in risk of overweight in school children with the installation of water fountains in their building. Building code changes have a broad reach. There is strong interest in increasing water consumption as an obesity prevention strategy, and more research in this area would be helpful.
REDUCE ACCESS TO AND CONSUMPTION OF CALORIE-DENSE, NUTRIENT-POOR FOODS
Strategy 8: Implement fiscal policies and local ordinances to discourage the consumption of calorie-dense, nutrient-poor foods and beverages (e.g., taxes, incentives, land use and zoning regulations).
Overall, the action steps listed for this strategy have limited evidence. However, there is some observational evidence supporting the use of land use and zoning policies related to fast food establishments near schools and residential
areas. The committee highlighted the action step: “Implement a tax strategy to discourage consumption of foods and beverages that have minimal nutritional value, such as sugar-sweetened beverages.” Although there is limited evidence on the impact of this action step, there is growing interest in its potential to reduce obesity, and its reach is likely to be broad. More research related to the implementation of this action step would be useful.
RAISE AWARENESS ABOUT THE IMPORTANCE OF HEALTHY EATING TO PREVENT CHILDHOOD OBESITY
Strategy 9: Promote media and social marketing campaigns on healthy eating and childhood obesity prevention.
There is intervention evidence supporting the action step that the committee highlighted for special consideration under this strategy: “Develop media campaigns, utilizing multiple channels to promote healthy eating using consistent messages.” In addition, this action step has the potential to reach a broad population, and more research on its impact would be valuable. The rest of the action steps under this strategy have limited evidence.
Actions for Increasing Physical Activity
ENCOURAGE PHYSICAL ACTIVITY
Strategy 1: Encourage walking and bicycling for transportation and recreation through improvements in the built environment.
Most of the action steps under this strategy are supported by observational evidence, including the action step the committee highlighted under this strategy: “Plan, build, and maintain a network of sidewalks and street crossings that creates a safe and comfortable walking environment and that connects to schools, parks, and other destinations.” Besides being supported by published research evidence, including recommendations by CDC’s Task Force on Community Preventive Services, this action step has the potential for reaching a large segment of the population.
Strategy 2: Promote programs that support walking and bicycling for transportation.
The majority of action steps under this strategy are supported by observational evidence. There is limited evidence on the impact of improved access
to bicycles and related equipment or increased transit use through reduced fares for children on physical activity. There are two action steps under this strategy that were highlighted by the committee: “Adopt community policing strategies that improve safety and security of streets, especially in higher crime neighborhoods” and “Collaborate with schools to develop and implement a Safe Routes to School program to increase the number of children safely walking and bicycling to schools.” Both are supported by observational evidence, and both have the potential to reach large numbers of people. More research in these areas would be helpful.
Strategy 3: Promote other forms of recreational physical activity.
The action steps under this strategy are supported by observational and intervention evidence. Two of the committee-highlighted action steps: “Build and maintain parks and playgrounds that are safe and attractive for playing, and in close proximity to residential areas” and “Adopt community policing strategies that improve safety and security for park use, especially in higher crime neighborhoods” are supported by observational evidence. The other highlighted strategy: “Collaborate with school districts and other organizations to establish joint use of facilities agreements for allowing playing fields, playgrounds and recreation centers to be used by community residents when schools are closed” is supported in part by intervention evidence from a study that examined the impact of opening neighborhood schoolyards on weekends and after school for children’s use. All three action steps have the potential for broad reach in the community, are of great interest to communities, and research on their effectiveness would be very useful.
Strategy 4: Promote policies that build physical activity into daily routines.
Overall, there is limited evidence for the action steps under this strategy, although there is observational evidence supporting the action step: “Develop worksite policies and practices that build physical activity into routines.” The committee highlighted for special consideration the action step: “Institute regulatory policies mandating minimum play space, physical equipment, and duration of play in preschool, after-school, and child-care programs.” This action step has limited evidence but there is observational evidence that the availability of play equipment increases physical activity in child care centers. This action step has the potential for broad reach because of the large number of children being cared for outside the home, and research on the effectiveness of this action step would
be very useful. There is also a growing interest in influencing children’s physical activity in child care centers and after school programs.
DECREASE SEDENTARY BEHAVIOR
Strategy 5: Promote policies that reduce sedentary screen time.
There is observational evidence supporting the action step under this strategy. Moreover, the CDC’s Task Force on Community Preventive Services recommends behavioral interventions to reduce screen time.
RAISE AWARENESS OF THE IMPORTANCE OF INCREASING PHYSICAL ACTIVITY
Strategy 6: Develop a social marketing program that emphasizes the multiple benefits for children and families of sustained physical activity.
The action step for this strategy that recommends “a social marketing program that emphasizes the multiple benefits for children and families of sustained physical activity” is supported by intervention evidence. The other action steps under this strategy have limited evidence.
As mentioned often in this report, the evidence base for local government actions is limited in certain areas, but steadily accumulating. The shortcomings in the evidence base should not discourage action, but should encourage continuing research, evaluation, and analysis whenever possible, especially in those areas in which evidence is lacking. When local governments evaluate the results of their childhood obesity prevention actions, it is important to ensure that this information is broadly disseminated.