Preventing Obesity In The US
Reported by:
Laura Kettel Khan, PhD; Kathleen Sobush, MS, MPH; Dana Keener, PhD; Kenneth Goodman, MA; Amy Lowry, MPA; Jakub Kakietek, MPH; Susan Zaro, MPH3
Summary
Approximately two thirds of U.S. adults and one fifth of U.S. children are obese or overweight.
During 1980--2004, obesity prevalence among U.S. adults doubled, and recent data indicate an estimated 33% of U.S. adults are overweight (body mass index [BMI] 25.0--29.9), 34% are obese (BMI ≥30.0), including nearly 6% who are extremely obese (BMI ≥40.0).
The prevalence of being overweight among children and adolescents increased substantially during 1999--2004, and approximately 17% of U.S. children and adolescents are overweight (defined as at or above the 95% percentile of the sex-specific BMI for age growth charts).
Being either obese or overweight increases the risk for many chronic diseases (e.g., heart disease, type 2 diabetes, certain cancers, and stroke). Reversing the U.S. obesity epidemic requires a comprehensive and coordinated approach that uses policy and environmental change to transform communities into places that support and promote healthy lifestyle choices for all U.S. residents.
Environmental factors (including lack of access to full-service grocery stores, increasing costs of healthy foods and the lower cost of unhealthy foods, and lack of access to safe places to play and exercise) all contribute to the increase in obesity rates by inhibiting or preventing healthy eating and active living behaviors.
Recommended strategies and appropriate measurements are needed to assess the effectiveness of community initiatives to create environments that promote good nutrition and physical activity. To help communities in this effort, CDC initiated the Common Community Measures for Obesity Prevention Project (the Measures Project). The objective of the Measures Project was to identify and recommend a set of strategies and associated measurements that communities and local governments can use to plan and monitor environmental and policy-level changes for obesity prevention.
This report describes the expert panel process that was used to identify 24 recommended strategies for obesity prevention and a suggested measurement for each strategy that communities can use to assess performance and track progress over time.
The 24 strategies are divided into six categories:
1) strategies to promote the availability of affordable healthy food and beverages),
2) strategies to support healthy food and beverage choices,
3) a strategy to encourage breastfeeding,
4) strategies to encourage physical activity or limit sedentary activity among children and youth, 5) strategies to create safe communities that support physical activity, and
6) a strategy to encourage communities to organize for change.
(Edited for length - honest!)
1. Communities Should Increase Availability of Healthier Food and Beverage Choices in Public Service Venues
Overview
Limited availability of healthier food and beverage options can be a barrier to healthy eating and drinking. Healthier food and beverage choices include, but are not limited to, low energy dense foods and beverages with low sugar, fat, and sodium content (11). Schools are a key venue for increasing the availability of healthier foods and beverages for children. Other public service venues positioned to influence the availability of healthier foods include after-school programs, child care centers, community recreational facilities (e.g., parks, playgrounds, and swimming pools), city and county buildings, prisons, and juvenile detention centers. Improving the availability of healthier food and beverage choices (e.g., fruits, vegetables, and water) might increase the consumption of healthier foods.
Evidence
CDC's Community Guide reports insufficient evidence to determine the effectiveness of multicomponent school-based nutrition initiatives designed to increase fruit and vegetable intake and decrease fat and saturated fat intake among school-aged children (22,23). However, systematic research reviews have reported an association between the availability of fruits and vegetables and increased consumption (24,25). Farm-to-school salad bar programs, which deliver produce from local farms to schools, have been shown to increase fruit and vegetable consumption among students (12). A 2-year randomized control trial of a school-based environmental intervention that increased the availability of lower-fat foods in cafeteria à la carte areas indicated that sales of lower-fat foods increased among adolescents attending schools exposed to the intervention (26).
2. Communities Should Improve Availability of Affordable Healthier Food and Beverage Choices in Public Service Venues
Overview
Healthier foods generally are more expensive than less-healthy foods (28), which can pose a significant barrier to purchasing and consuming healthier foods, particularly for low-income consumers. Healthier foods and beverages include, but are not limited to, foods and beverages with low energy density and low calorie, sugar, fat, and sodium content (11). Healthier food and beverage choices need to be both available and affordable for persons to consume them.
Strategies to improve the affordability of healthier foods and beverages include lowering prices of healthier foods and beverages and providing discount coupons, vouchers redeemable for healthier foods, and bonuses tied to the purchase of healthier foods. Pricing strategies create incentives for purchasing and consuming healthier foods and beverages by lowering the prices of such items relative to less healthy foods. Pricing strategies that can be applied in public service venues (e.g., schools and recreation centers) include, but are not limited to, decreasing the prices of healthier foods sold in vending machines and in cafeterias and increasing the price of less healthy foods and beverages at concession stands.
Evidence
Research has demonstrated that reducing the cost of healthier foods increases the purchase of healthier foods (29,30). For example, one study indicated that sales of fruits and carrots in high-school cafeterias increased after prices were reduced (31). In addition, interventions that reduced the price of healthier, low-fat snacks in vending machines in school and work settings have been demonstrated to increase purchasing of healthier snacks (32,33). A recent study estimated that a subsidized 10% price reduction on fruits and vegetables would encourage low-income persons to increase their daily consumption of fruits from 0.96 cup to 0.98--1.01 cups and increase their daily consumption of vegetables from 1.43 cups to 1.46--1.50 cups, compared with the recommended 1.80 cups of fruits and 2.60 cups of vegetables (34).
Furthermore, interventions that provide coupons redeemable for healthier foods and bonuses tied to the purchase of healthier foods increase purchase and consumption of healthier foods in diverse populations, including university students, recipients of services from the Supplemental Nutrition Program for Women, Infants, and Children (WIC), and low-income seniors (35--37). For example, one community-based intervention indicated that WIC recipients who received weekly $10 vouchers for fresh produce increased their consumption of fruits and vegetables compared with a control group and sustained the increase 6 months after the intervention (38).
3. Communities Should Improve Geographic Availability of Supermarkets in Underserved Areas
Overview
Supermarkets and full-service grocery stores have a larger selection of healthy food (e.g., fruits and vegetables) at lower prices compared with smaller grocery stores and convenience stores. However, research suggests that low-income, minority, and rural communities have fewer supermarkets as compared with more affluent areas (39,40). Increasing the number of supermarkets in areas where they are unavailable or where availability is limited is might increase access to healthy foods, particularly for economically disadvantaged populations.
Evidence
Greater access to nearby supermarkets is associated with healthier eating behaviors (39). For example, a cross-sectional study of approximately 10,000 participants indicated that blacks living in neighborhoods with at least one supermarket were more likely to consume the recommended amount of fruits and vegetables than blacks living in neighborhoods without supermarkets. Further, blacks consumed 32% more fruits and vegetables for each additional supermarket located in their census tract (41). Another study indicated that increasing the number of supermarkets in underserved neighbors increased real estate values, increased economic activity and employment, and resulted in lower food prices (42).
One cross-sectional study linked height and weight data from approximately 70,000 adolescents to data on food store availability (43). The results indicated that, after controlling for socioeconomic status, greater availability of supermarkets was associated with lower adolescent BMI scores and that a higher prevalence of convenience stores was related to higher BMI among students. The association between supermarket availability and weight was stronger for black students and for students whose mothers worked full-time (43).
4. Communities Should Provide Incentives to Food Retailers to Locate in and/or Offer Healthier Food and Beverage Choices in Underserved Areas
Overview
Healthier foods and beverages include but are not limited to foods and beverages with low energy density and low calorie, sugar, fat, and sodium content as defined by IOM (11). Disparities in the availability of healthier foods and beverages between communities with different income levels, ethnic composition, and other characteristics are well documented, and limited availability of healthier food and beverage choices in underserved communities constitutes a substantial barrier to improving nutrition and preventing obesity (41).
To address this issue, communities can provide incentives to food retailers (e.g., supermarkets, grocery stores, convenience and corner stores, and street vendors) to offer a greater variety of healthier food and beverage choices in underserved areas. Such incentives, both financial and nonfinancial, can be offered to encourage opening new retail outlets in areas with limited shopping options, and existing corner and convenience stores (which typically depend on sales of alcohol, tobacco, and sugar-sweetened beverages) into neighborhood groceries selling healthier foods (44). Financial incentives include but are not limited to tax benefits and discounts, loans, loan guarantees, and grants to cover start-up and investment costs (e.g., improving refrigeration and warehouse capacity). Nonfinancial incentives include supportive zoning, and increasing the capacity of small businesses through technical assistance in starting up and maintaining sales of healthier foods and beverages.
Evidence
The presence of retail venues that provide healthier foods and beverages is associated with better nutrition. Cross-sectional studies indicate that the presence of retail venues offering healthier food and beverage choices is associated with increased consumption of fruits and vegetables and lower BMI (45). One study indicated that every additional supermarket within a given census tract was associated with a 32% increase in the amount of fruits and vegetables consumed by persons living in that census tract (40). Another study indicated that greater availability of supermarkets was associated with lower adolescent BMI scores and a higher prevalence of convenience stores was related to higher BMI among students (43). The association between supermarket availability and weight was stronger for black students compared with white and Hispanic students, and stronger for students whose mothers work full-time compared with those whose mothers work part-time or do not work (43).
5. Communities Should Improve Availability of Mechanisms for Purchasing Foods from Farms
Overview
Mechanisms for purchasing food directly from farms include farmers' markets, farm stands, community-supported agriculture, "pick your own," and farm-to-school initiatives. Experts suggest that these mechanisms have the potential to increase opportunities to consume healthier foods, such as fresh fruits and vegetables, by possibly reducing costs of fresh foods through direct sales; making fresh foods available in areas without supermarkets; and harvesting fruits and vegetables at ripeness rather than at a time conducive to shipping, which might improve their nutritional value and taste (M. Hamm, PhD, Michigan State University, personal communication, 2008).
Evidence
Evidence supporting a direct link between purchasing foods from farms and improved diet is limited. Two studies of initiatives to encourage participation in the Seniors Farmers' Market Nutrition Program (46) and the WIC Farmers' Market Nutrition Program (47) report either increased intention to eat more fruits and vegetables or increased utilization of the program; however, neither study reported direct evidence that the programs resulted in increased consumption of fruits and vegetables. The Farmers' Market Salad Bar Program in the Santa Monica--Malibu Unified School District aims to increase students' consumption of fresh fruits and vegetables and to support local farmers by purchasing produce directly from local farmers' markets and serving them in the district's school lunch program. An evaluation of the program over a 2-year period demonstrated that 30%--50% of students chose the salad bar on any given day (48). Access to farm foods varies between agricultural and metropolitan areas.
6. Communities Should Provide Incentives for the Production, Distribution, and Procurement of Foods from Local Farms
Overview
Currently the United States is not producing enough fruits, vegetables, whole grains, and dairy products for all U.S. citizens to eat the quantities of these foods recommended by the USDA Dietary Guidelines for Americans (27,49). Providing incentives to encourage the production, distribution, and procurement of food from local farms aims might increase the availability and consumption of locally produced foods by community residents, enhance the ability of the food system to provide sufficient quantities of healthier foods, and increase the viability of local farms and food security for communities (M. Hamm, PhD, Michigan State University, personal communication, 2008). Definitions of "local" vary by place and context but may include the area of the foodshed (i.e. a geographic area that supplies a population center with food), food grown within a day's driving distance of the place of sale, or a smaller area such as a city and its surroundings. Incentives to encourage local food production can include forming grower cooperatives, instituting revolving loan funds, and building markets for local farm products through economic development and through collaborations with the Cooperative Extension Service (50). Additional incentives include but are not limited to farmland preservation, marketing of local crops, zoning variances, subsidies, streamlined license and permit processes, and the provision of technical assistance.
Evidence
Evidence suggests that dispersing agricultural production in local areas around the country (e.g., through local farms and urban agriculture) would increase the amount of produce that could be grown and made available to local consumers, improve economic development at the local level (51,52), and contribute to environmental sustainability (53). Although no evidence has been published to link local food production and health outcomes, a study has been funded to explore the potential nutritional and health benefits of eating locally grown foods (A. Ammerman, DrPH, University of North Carolina Center for Health Promotion and Disease Prevention, personal communication, 2009).
7. Communities Should Restrict Availability of Less Healthy Foods and Beverages in Public Service Venues
Overview
Less healthy foods and beverages include foods and beverages with a high calorie, fat, sugar, and sodium content, and a low nutrient content. Less healthy foods are more available than healthier foods in U.S. schools (54). The availability of less healthy foods in schools is inversely associated with fruit and vegetable consumption and is positively associated with fat intake among students (55). Therefore, restricting access to unhealthy food options is one component of a comprehensive plan for better nutrition.
Schools can restrict the availability of less healthy foods by setting standards for the types of foods sold, restricting access to vending machines, banning snack foods and food as rewards in classrooms, prohibiting food sales at certain times of the school day, or changing the locations where unhealthy competitive foods are sold. Other public service venues that could also restrict the availability of less healthy foods include after-school programs, regulated child care centers, community recreational facilities (e.g., parks, recreation centers, playgrounds, and swimming pools), city and county buildings, and prisons and juvenile detention centers.
Evidence
No peer-reviewed studies were identified that examined the impact of interventions designed to restrict the availability of less healthy foods in public service venues. Federal nutritional guidelines prohibit the sale of foods of "minimal nutritional value" in school cafeterias while meals are being served. However, the guidelines currently do not prevent or restrict the sale of these foods in vending machines near the cafeteria or in other school locations (11). Certain states and school districts have developed more restrictive policies regarding competitive foods; 21 states have policies that restrict the sale of competitive foods beyond USDA regulations (56). However, no studies were identified that examined the impact of the policies in those states on student eating behavior.
8. Communities Should Institute Smaller Portion Size Options in Public Service Venues
Overview
Portion size can be defined as the amount (e.g. weight, calorie content, or volume) of a single food item served in a single eating occasion (e.g. a meal or a snack), such as the amount offered to a person in a restaurant, in the packaging of prepared foods, or the amount a person chooses to put on his or her plate (23). Controlling portion size is important because research has demonstrated that persons often either 1) do not notice differences in portion sizes and unknowingly eat larger amounts when presented with a larger portion or 2) when eating larger portions, do not consume fewer calories at subsequent meals or during the rest of the day (57).
Evidence
Evidence is lacking to demonstrate the effectiveness of population-based interventions aimed at reducing portion sizes in public service venues. However, evidence from clinical studies conducted in laboratory settings demonstrates that decreasing portion size decreases energy intake (58--60). This finding holds across a wide variety of foods and different types of portions (e.g., portions served on a plate, sandwiches, or prepackaged foods such as potato chips). Clinical studies conducted in nonlaboratory settings demonstrate that increased portion size leads to increased energy intake (61,62). The majority of studies that evaluated the impact of portion size on nutritional outcomes were short term, producing little evidence regarding the long-term impact of portion size on eating patterns, nutrition, and obesity (23). Intervention studies are underway that evaluate the impact of limiting portion size, combined with other strategies to prevent obesity in workplaces (63).
9. Communities Should Limit Advertisements of Less Healthy Foods and Beverages
Overview
Research has demonstrated that more than half of television advertisements viewed by children and adolescents are food-related; the majority of them promote fast foods, snack foods, sweets, sugar-sweetened beverage products, and other less healthy foods that are easily purchased by youths (11). In 2006, major food and beverage marketers spent $1.6 billion to promote food and beverage products among children and adolescents in the United States (64). Television advertising has been determined to influence children to prefer and request high-calorie and low-nutrient foods and beverages and influences short-term consumption among children aged 2--11 years (65). Therefore, limiting advertisements of less healthy foods might decrease the purchase and consumption of such products. Legislation to limit advertising of less healthy foods and beverages usually is introduced at the federal or state level. However, local governing bodies, such as district level school boards, might have the authority to limit advertisements of less healthy foods and beverages in areas within their jurisdiction (9).
Evidence
Little evidence is available regarding the impact of restricting advertising on purchasing and consumption of less healthy foods (11,22,66,67). However, cross-sectional time-series studies of tobacco-control efforts suggest that an association exists between advertising bans and decreased tobacco consumption (22,68). One study estimated that a ban on fast-food advertising on children's television programs could reduce the number of overweight children aged 3--11 years by 18% and the number of overweight adolescents aged 12--18 years by 14% (69). Limited bans of advertising, which include some media but not others (e.g., television but not newspapers), might have little or no effect as the food and beverage industry might redirect its advertising efforts to media not included in the ban, thus limiting researchers' ability to detect causal effects (68).
10. Communities Should Discourage Consumption of Sugar-Sweetened Beverages
Overview
Consumption of sugar-sweetened beverages (e.g., carbonated soft drinks, sports drinks, flavored sweetened milk, and fruit drinks) among children and adolescents has increased dramatically since the 1970s and is associated with higher daily caloric intake and greater risk of obesity (70). Although consumption of sugar-sweetened beverages occurs most often in the home, schools and child care centers also contribute to the problem either by serving sugar-sweetened beverages or by allowing children to purchase sugar-sweetened beverages from vending machines (70). Policies that restrict the availability of sugar-sweetened beverages and 100% fruit juice in schools and child care centers might discourage the consumption of high-caloric beverages among children and adolescents.
Evidence
One longitudinal study of a school-based environmental intervention conducted among Native American high school students that combined education to decrease the consumption of sugar-sweetened beverages and increase knowledge of diabetes risk factors with the development of a youth-oriented fitness center demonstrated a substantial reduction in consumption of sugar-sweetened beverages for a 3-year period (71). A randomized control study of a home-based environmental intervention that eliminated sugar-sweetened beverages from the homes of a diverse group of adolescents demonstrated that, among heavier adolescents, the intervention resulted in significantly (p = 0.03) greater reduction in BMI scores compared with the control group (72).
11. Communities Should Increase Support for Breastfeeding
Overview
Exclusive breastfeeding is recommended for the first 4--6 months of life, and breastfeeding together with the age-appropriate introduction of complementary foods is encouraged for the first year of life. Epidemiologic data suggest that breastfeeding provides a limited degree of protection against childhood obesity, although the reasons for this association are not clear (11). Breastfeeding is thought to promote an infant's ability to self regulate energy intake, thereby allowing him or her to eat in response to internal hunger and satiety cues (73). Some research suggests that the metabolic/hormonal cues provided by breastmilk contribute to the protective association between breastfeeding and childhood obesity (74). Despite the many advantages of breastfeeding, many women choose to bottle-feed their babies for a variety of reasons, including social and structural barriers to breastfeeding, such as attitudes and policies regarding breastfeeding in health-care settings and public and work places (75).
Breastfeeding support programs aim to increase the initiation and exclusivity rate of breastfeeding and to extend the duration of breastfeeding. Such programs include a variety of interventions in hospitals and workplaces (e.g., setting up breastfeeding facilities, creating a flexible work environment that allows breastfed infants to be brought to work, providing onsite child care services, and providing paid maternity leaves), and maternity care (e.g., polices and staff training programs that promote early breastfeeding initiation, restricting the availability of supplements or pacifiers, and providing facilities that accommodate mothers and babies). The CDC Guide to Breastfeeding Interventions identifies the following general areas of interventions and programs as effective in supporting breastfeeding: 1) maternity care practices, 2) support for breastfeeding in the workplace, 3) peer support, 4) educating mothers, 5) professional support, and 6) media and community-wide campaigns (76).
Evidence
Evidence directly linking environmental interventions that support breastfeeding with obesity-related outcomes is lacking. However, systematic reviews of epidemiologic studies indicate that breastfeeding helps prevent pediatric obesity: breastfed infants were 13%--22% less likely to be obese than formula-fed infants (77,78), and each additional month of breastfeeding was associated with a 4% decrease in the risk of obesity (79). Furthermore, one study demonstrated that infants fed with low (<20%>80% of feedings from breastmilk) (80).
Systematic reviews indicate that support programs in health-care settings are effective in increasing rates of breastfeeding initiation and in preventing early cessation of breastfeeding. Training medical personnel and lay volunteers to promote breastfeeding decreases the risk for early cessation of breastfeeding by 10% (81) and that education programs increase the likelihood of the initiation of breastfeeding among low-income women in the United States by approximately twofold (75).
One systematic review did not identify any randomized control trials that have tested the effectiveness of workplace-wide interventions promoting breastfeeding among women returning to paid employment (82). However, one study demonstrated that women who directly breastfed their infant at work and/or pumped breast milk at work breastfed at a higher intensity than women who did not breastfeed or pump breast milk at work (83). Furthermore, evaluations of individual interventions aimed at supporting breastfeeding in the workplace demonstrate increased initiation rates and duration of breastfeeding compared with national averages (76).
12. Communities Should Require Physical Education in Schools
Overview
This strategy supports the Healthy People 2010 objective (objective no. 22.8) to increase the proportion of the nation's public and private schools that require daily PE for all students (15). The National Association for Sport and Physical Education (NASPE) and the American Heart Association (AHA) recommend that all elementary school students should participate in >150 minutes per week of PE and that all middle and high school students should participate in >225 minutes of PE per week for the entire school year (84). School-based PE increases students' level of physical activity and improves physical fitness (23).
Many states mandate some level of PE in schools: 36 states mandate PE for elementary-school students, 33 states mandate PE for middle-school students, and 42 states mandate PE for high-school students (84). However, to what extent these requirements are enforced is unclear, and only two states (Louisiana and New Jersey) mandate the recommended >150 minutes per week of PE classes. Potential barriers to implementing PE classes in schools include concerns among school administrators that PE classes compete with traditional academic curricula or might detract from students' academic performance. However, a Community Guide review identified no evidence that time spent in PE classes harms academic performance (23).
Evidence
In a systematic review of 14 studies, the Community Guide demonstrated that school-based PE was effective in increasing levels of physical activity and improving physical fitness (23). The review included studies of interventions that increased the amount of time spent in PE classes, the amount of time students are active during PE classes, or the amount of moderate or vigorous physical activity (MVPA) students engage in during PE classes.
Most studies that correlated school-based PE classes and the physical activity and fitness of students focused on the quality and duration of PE classes (e.g., the amount of physical activity during class, the amount of MVPA) rather than simply whether PE was required. However, requiring that PE classes be taught in schools is a necessary minimum condition for measuring the effectiveness of efforts to improve school-based PE class curricula.
13. Communities Should Increase the Amount of Physical Activity in PE Programs in Schools
Overview
Time spent in PE classes does not necessarily mean that students are physically active during that time. Increasing the amount of physical activity in school-based PE classes has been demonstrated to be effective in increasing fitness among children. Specifically, increasing the amount of time children are physically active in class, increasing the number of children moving as part of a game or activity (e.g., by modifying game rules so that more students are moving at any given time, or by changing activities to those where all participants stay active), and increasing the amount of moderate to vigorous activity during class time are effective strategies for increasing physical activity.
Evidence
In a review of 14 studies, the Community Guide demonstrated strong evidence of effectiveness for enhancing PE classes taught in school by increasing the amount of time students spend in PE class, the amount of time they are active during PE classes, or the amount of MVPA they engage in during PE classes (23). The median effect of modifying school PE curricula as recommended was an 8% increase in aerobic fitness among school-aged children. Modifying school PE curricula was effective in increasing physical activity across racial, ethnic, and socioeconomic populations, among males and females, in elementary and high schools, and in urban and rural settings.
A quasi-experimental study of the Sports, Play, and Active Recreation for Kids (SPARK) school PE program, which is designed to maximize participation in physical activity during PE classes, demonstrated that the program increased physical activity during PE classes but the effect did not carry over outside of school (85). The study identified no significant effects on fitness levels among boys (p = 29--55), but girls in the classes led by a PE specialist were superior in abdominal and cardio respiratory endurance to girls in the control condition (p = 0.03). The Child and Adolescent Trial for Cardiovascular Health (CATCH) is another intervention which aims to increase MVPA in children during PE classes. A randomized, controlled field trail of CATCH that was conducted with more than 5,000 third-grade students from 96 public schools over a 3-year period indicated that the intensity of physical activity in PE classes (class time devoted to MVPA) during the intervention increased significantly in the intervention schools compared with the control schools (p<0.02) (86).
The background and training of teachers who deliver PE curricula might mediate the effect of interventions on physical activity. For example, one study indicated that SPARK classes led by PE specialists spent more time per week in physical activity (40 minutes) than classes led by regular teachers who had received training in the curriculum (33 minutes) (85).
14. Communities Should Increase Opportunities for Extracurricular Physical Activity
Overview
Opportunities for extracurricular physical activity outside of school hours to complement formal PE increasingly are an important strategy to prevent obesity in children and youth (11). This strategy focuses on noncompetitive physical activity opportunities such as games and dance classes available through community and after-school programs, and excludes participation in varsity team sports or sport clubs, which require tryouts and are not open to all students. Research has demonstrated that after-school programs that provide opportunities for extracurricular physical activity increase children's level of physical activity and improve other obesity-related outcomes.
Evidence
Intervention studies have demonstrated that participation in after-school programs that provided opportunities for extracurricular physical activity held both at schools and other community settings increased participants' level of physical activity (87,88) and improved obesity-related outcomes, such as improved cardiovascular fitness and reduced body fat content (89). Two pilot studies demonstrated that providing opportunities for extracurricular physical activity increased levels of physical activity (90) and decreased sedentary behavior (91) among participants.
The Promoting Life Activity in Youth (PLAY) program is designed to teach active lifestyle habits to children and help them to accumulate 30--60 minutes of moderate to vigorous physical activity per day. One study indicated that participation in PLAY and PE had a significant impact on physical activity among girls (p<0.001) but not for boys (90). Lack of access is a barrier that might limit the impact of increased availability of opportunities for extracurricular physical activity. In East Palo Alto, California, where the city provided buses from schools to the community center, 70% of the eligible girls attended dance classes at least 2 days a week. In Oakland, where the city did not provide buses, only 33% of eligible girls attended the class two or more times a week (91).
15. Communities Should Reduce Screen Time in Public Service Venues
Overview
Mechanisms linking extended screen viewing time and obesity include displacement of physical activity; a reduction in metabolic rate and excess energy intake; and increased consumption of food advertised on television as a result of exposure to marketing of high energy dense foods and beverages (92,93). The American Academy of Pediatrics (94) recommends that parents limit children's television time to no more than to 2 hours per day. Although only a relatively small portion of television viewing and computer and video game use occurs in public service venues such as schools, day care centers, and after-school programs, local policymakers can intervene to limit screen viewing time among children and youth in these venues.
Evidence
Long-term cohort studies have demonstrated a positive significant (p = 0.02) association between television viewing in childhood and body mass index levels in adulthood (92,93). In addition, a cross-sectional study indicated that the amount of time spent watching TV/video was significantly related to overweight among low-income preschool children (p<0.004) (95). A randomized controlled school-based trial indicated that children who reduced their television, videotape, and video game use had significant decreases in BMI (p = 0.002), tricep skin fold thickness (p = 0.002), and waist circumference (p<0.001) compared with children in control groups (96). The evidence surrounding children's television viewing and its relationship to physical activity has been somewhat inconsistent. A review evaluating correlates of childhood physical activity determined that some studies find time spent engaged in sedentary activities, specifically TV viewing and video use, has a negative association to physical activity, while other studies find no relationship (97). Multicomponent school-based intervention studies have demonstrated that spending less time watching television is associated with increased physical activity (98) and decreased risk of childhood obesity among girls but not boys (99).
16. Communities Should Improve Access to Outdoor Recreational Facilities
Overview
Recreation facilities provide space for community members to engage in physical activity and include places such as parks and green space, outdoor sports fields and facilities, walking and biking trails, public pools, and community playgrounds. Accessibility of recreation facilities depends on a number of factors such as proximity to homes or schools, cost, hours of operation, and ease of access. Improving access to recreation facilities and places might increase physical activity among children and adolescents.
Evidence
In a review based on 10 studies, the Community Guide concluded that efforts to increase access to places for physical activity, when combined with informational outreach, can be effective in increasing physical activity (100). The studies reviewed by the Community Guide included interventions such as creating walking trails, building exercise facilities, and providing access to existing facilities. However, it was not possible to separate the benefits of improved access to places for physical activity from health education and services that were provided concurrently (100).
A comprehensive review of 108 studies indicated that access to facilities and programs for recreation near their homes, and time spent outdoors, correlated positively with increased physical activity among children and adolescents (97). A study that analyzed data from a longitudinal survey of 17,766 adolescents indicated that those who used community recreation centers were significantly more likely to engage in moderate to vigorous physical activity (p≤0.00001) (101).
A multivariate analysis indicated that self-reported access to a park, and the perception that footpaths are safe for walking were significantly associated with adult respondents being classified as physically active at a level sufficient for health benefits (102). Another study that used self-report and GIS data concluded that longer distances and the presence of barriers (e.g., busy streets and steep hills) between individuals and bike paths were associated with non-use of bike paths (103).
17. Communities Should Enhance Infrastructure Supporting Bicycling
Overview
Enhancing infrastructure supporting bicycling includes creating bike lanes, shared-use paths, and routes on existing and new roads; and providing bike racks in the vicinity of commercial and other public spaces. Improving bicycling infrastructure can be effective in increasing frequency of cycling for utilitarian purposes (e.g., commuting to work and school, bicycling for errands). Research demonstrates a strong association between bicycling infrastructure and frequency of bicycling.
Evidence
Longitudinal intervention studies have demonstrated that improving bicycling infrastructure is associated with increased frequency of bicycling (104,105). Cross-sectional studies indicated a significant association between bicycling infrastructure and frequency of biking (p<0.001) (103,106,107).
18. Communities Should Enhance Infrastructure Supporting Walking
Overview
Infrastructure that supports walking includes but is not limited to sidewalks, footpaths, walking trails, and pedestrian crossings. Walking is a regular, moderate-intensity physical activity in which relatively large numbers of persons can engage. Well-developed infrastructure supporting walking is an important element of the built environment and has been demonstrated to be associated with physical activity in adults and children. Interventions aimed at supporting infrastructure for walking are included in street-scale urban design and land use interventions that support physical activity in small geographic areas. These interventions can include improved street lighting, infrastructure projects to increase the safety of street crossings, use of traffic calming approaches (e.g., speed humps and traffic circles), and enhancing street landscaping (108).
Evidence
The Community Guide reports sufficient evidence that street-scale urban design and land use policies that support walking are effective in increasing levels of physical activity (108). Reviews of cross-sectional studies of environmental correlates of physical activity and walking generally find a positive association between infrastructure supportive of walking and physical activity (109,110). However, some systematic reviews indicated no evidence of an association between the presence of sidewalks and physical activity (111). Other reviews indicated associations, but only for certain subgroups of subjects (e.g., men and users of longer walking trails) (108,109). Intervention studies demonstrate effectiveness of enhanced walking infrastructure when combined with other strategies. For example, evaluation of the Marin County Safe Routes to School program indicated that identifying and creating safe routes to school, together with educational components, increased the number of students walking to school (105). When considering the evidence for this strategy, planners should note that physically active individuals might be more likely to locate in communities that have an existing infrastructure for walking, which might produce spurious correlations in cross-sectional studies (109).
19. Communities Should Support Locating Schools within Easy Walking Distance of Residential Areas
Overview
Walking to and from school has been demonstrated to increase physical activity among children during the commute, leading to increased energy expenditure and potentially to reduced obesity. However, the percentage of students walking to school has dropped dramatically over the past 40 years, partially due to the increased distance between children's homes and schools. Current land use trends and policies pose barriers to building smaller schools located near residential areas. Therefore, requisite activities that support locating schools within easy walking distance of residential areas include efforts to change land use and school system policies.
Evidence
The Community Guide indicated that community-scale urban design and land use policies and practices, including locating schools, stores, workplaces, and recreation areas close to residential areas, are effective in facilitating an increase in levels of physical activity (23,108). A simulation modeling study conducted by the U.S. Environmental Protection Agency (EPA) in Florida indicated that school location as well as the quality of the built environment between home and school has an effect on walking and biking to school. Specifically, this combination of school location and built environment quality would produce a 13% increase in nonmotorized travel to school (112). A cross-sectional study in the Philippines indicated that adolescents who walked to school expended significantly more energy than those who used motorized modes of transport. This association was not explainable by in-school or after-school sports or exercise. Assuming no change takes place in energy intake, the difference in energy expenditure between transport modes would lead to an expected 2--3-pound annual weight gain by youth who commute to school by motorized transport (113).
As a result of current land use trends and policies regarding school siting, very little work has been done to locate schools within neighborhoods. A study conducted by the Environmental Protection Agency suggests that the trend of building larger schools with larger catchment areas should be reversed to locate schools within neighborhoods (112). The distance between homes and schools is not the only factor that affects whether children walk to and from school. Among students living within 1 mile of school, the percentage of walkers fell from 90% to 31% between 1969 and 2001 (112). The decrease in walking to and from school has been attributed to a poor walking environment, defined as a built environment that has low population densities, little mixing of land uses, long blocks, and incomplete sidewalks (112). The majority of efforts to encourage walking to and from school involve improving the routes (e.g., Marin County's Safe Routes to School program) rather than improving the location of schools. Previous studies have recommended that local governments and school districts should ensure that children and youth have safe walking and bicycling routes between their homes and schools and encouraged their use (11).
20. Communities Should Improve Access to Public Transportation
Overview
Public transportation includes mass transit systems such as buses, light rail, street cars, commuter trains, and subways, and the infrastructure supporting these systems (e.g., transit stops and dedicated bus lanes). Improving access to public transportation encourages the use of public transit, which might, in turn, increase the level of physical activity when transit users walk or ride bicycles to and from transit access points.
Evidence
The Community Guide identified insufficient evidence to determine the effectiveness of transportation and travel policies and practices in increasing the level of physical activity or improving fitness because only one study of adequate quality was available (108). In a study that analyzed data from the 2001 National Household Travel Survey, researchers indicated that 29% of individuals who walk to and from public transit achieve at least 30 minutes of daily physical activity (114). Another study indicated that access to public transit was associated with decreases in the odds of using automobiles as a preferred mode of transportation and increases in the odds of walking and/or bicycling (115). In a cross-sectional study carried out in four San Francisco neighborhoods, researchers indicated that individuals with easy access to the Bay Area Rapid Transit System (BART) made, on average, 0.66 more nonmotorized trips than those who did not have access to BART (116).
Physically active individuals might be more likely to locate into communities with an infrastructure that supports physical activity, including neighborhoods with infrastructure supporting public transportation (110). Most neighborhood-level cross-sectional studies do not control for individual-level characteristics (e.g., ethnicity, age, socioeconomic status). Environmental factors, including infrastructure for public transit, also might affect different subpopulations differently (110,116).
21. Communities Should Zone for Mixed-Use Development
Overview
Zoning for mixed-use development is one type of community-scale land use policy and practice that allows residential, commercial, institutional, and other public land uses to be located in close proximity to one another. Mixed-use development decreases the distance between destinations (e.g., home and shopping), which has been demonstrated to decrease the number of trips persons make by automobile and increase the number of trips persons make on foot or by bicycle. Zoning regulations that accommodate mixed land use could increase physical activity by encouraging walking and bicycling trips for nonrecreational purposes. Zoning laws restricting the mixing of residential and nonresidential uses and encouraging single-use development can be a barrier to physical activity.
Evidence
The Community Guide lists mixed-use development and diversity of residential and commercial developments as examples of community-scale urban design and land use policies and practices (23). The Community Guide rated the evidence for community-scale urban design and land use policies and practices as sufficient to justify a recommendation that these characteristics increase physical activity (23,108). The recommendation was based on a review of 12 studies in which the median improvement in some aspect of physical activity was 161% (23,108).
Studies using correlation analyses and regression models indicated that mixed land use was associated with increased walking and cycling (110,117--119). A review of quasi-experimental studies indicated residents from high walkability neighborhoods (defined by higher density, greater connectivity, and more land use mix) reported twice as many walking trips per week than residents from low walkability neighborhoods (defined by low density, poor connectivity, and single land uses) (110). A cross-sectional study conducted in Atlanta, GA indicated that odds of obesity declined as mixed land use increased (118).
Some increased level of physical activity among residents of mixed-use neighborhoods might be attributable to selection of these types of neighborhoods by persons more likely to engage in physical activity (119). Mixed-use development is often combined with multiple design elements from urban planning and policy, including density, connectivity, roadway design, and walkability.
22. Communities Should Enhance Personal Safety in Areas Where Persons Are or Could Be Physically Active
Overview
Personal safety is affected by crime rates and other nontraffic-related hazards that exist in communities. Limited but supportive evidence indicates that improving community safety might be effective at increasing levels of physical activity in adults and children. In addition, safety considerations affect parents' decisions to allow their children to play and walk outside (11). Interventions to improve safety, such as increasing police presence, decreasing the number of abandoned buildings and homes, and improving street lighting, can be undertaken by individual communities.
Evidence
Cross-sectional studies have demonstrated a negative relationship between crime rates and/or perceived safety and physical activity in neighborhoods, particularly among adolescents (101,120,121). A systematic review indicated that observational measurements of safety (e.g., crime incidence) were negatively associated with physical activity, but subjective measurements (self-reported safety) were not correlated with physical activity (120).
Few intervention studies have evaluated the impact of policies and practices to improve personal safety on physical activity. However, one study indicated that improved street lighting in London led to reduced crime rates, less fear of crime, and more pedestrian street use (122). Some studies suggest that the relationship between safety and physical activity might vary by gender and/or other individual-level characteristics. For example, one study indicated that incidence rates of violent crimes were associated with lower physical activity in adolescent girls, but not in boys (121).
Persons of lower socioeconomic status depend more on walking as a means of transportation as compared with those of higher socioeconomic status, and they also are more likely to live in neighborhoods that are unsafe (11). This could explain why some studies do not find a positive association between perceived safety and physical activity. Reducing crime levels might require complex, multisectoral, and long-term efforts, which might go beyond the authority and capacity of local communities.
23. Communities Should Enhance Traffic Safety in Areas Where Persons Are or Could Be Physically Active
Overview
Traffic safety is the security of pedestrians and bicyclists from motorized traffic. Traffic safety can be enhanced by engineering streets for lower speeds or by retrofitting existing streets with traffic calming measurements (e.g., speed tables and traffic circles). Traffic safety can also be enhanced by developing infrastructure to improve the safety of street crossings (e.g., raised crosswalks and textured pavement) for nonmotorized traffic and for pedestrians.
The lack of safe places to walk, run, and bicycle as a result of real or perceived traffic hazards can deter children and adults from being physically active. Enhancing traffic safety has been demonstrated to be effective in increasing levels of physical activity in adults and children. Research suggests that persons living in neighborhoods with higher traffic safety are more physically active.
Evidence
The Community Guide reviewed both community-scale and street-scale urban design and land use policies and practices, including interventions aimed at improving traffic safety. The review indicated that both community-scale and street-scale policies and practices were effective in increasing physical activity (108). On the basis of sufficient evidence of effectiveness, the Community Guide recommends implementing community-scale and street-scale urban design and land use policies to promote physical activity, including design components to improve street lighting, infrastructure projects to increase safety of pedestrian street crossings, and use of traffic calming approaches such as speed humps and traffic circles (23).
A review of 19 studies examined the effects of environmental factors on physical activity, five of which considered traffic safety (123). One study demonstrated significant effects of traffic safety on increased physical activity (102).
24. Communities Should Participate in Community Coalitions or Partnerships to Address Obesity
Overview
Community coalitions consist of public- and private-sector organizations that, together with individual citizens, work to achieve a shared goal through the coordinated use of resources, leadership, and action (11). Potential stakeholders in community coalitions aimed at obesity prevention include but are not limited to community organizations and leaders, health-care professionals, local and state public health agencies, industries (e.g., building and construction, restaurant, food and beverage, and entertainment), the media, educational institutions, government (including transportation and parks and recreation departments), youth-related and faith-based organizations, nonprofit organizations and foundations, and employers.
The effectiveness of community coalitions stems from the multiple perspectives, talents, and expertise that are brought together to work toward a common goal. In addition, coalitions build a sense of community, enhance residents' engagement in community life, and provide a vehicle for community empowerment. Research in tobacco control demonstrates that the presence of antismoking community coalitions is associated with lower rates of cigarette use. Based on this research, it is plausible that community coalitions might be effective in preventing obesity and in improving physical activity and nutrition.
Evidence
Little evidence is available to determine the impact of community coalitions on obesity prevention (11). However, tobacco-control literature demonstrates that the presence of antismoking community coalitions is associated with lower rates of tobacco consumption. One study indicated that states with a greater number of anti-tobacco coalitions had lower per capita cigarette consumption than states with a lower number of coalitions (124).
Next Steps
The next step for this project is to disseminate the recommended community strategies and suggested measurements for use by local governments and communities throughout the United States. To help accomplish this, an implementation and measurement guide will be published and made available through the CDC website (available at http://www.cdc.gov/nccdphp/dnpao/publications/index.html). In addition, the measurements will be integrated into a new survey module that will be available to all members of ICMA's Center for Performance Measurement. Dissemination of these recommended obesity prevention strategies and proposed measurements is intended to inspire communities to consider implementing new policy and environmental change initiatives aimed at reversing the obesity epidemic. The recommended strategies and suggested measurements outlined in this report are being pilot tested in the Minnesota and Massachusetts state surveillance systems (Laura Hutton, MA, Minnesota Department of Health, personal communication, 2009; Maya Mohan, MPH, Massachusetts Department of Health, personal communication, 2009).
Laura Kettel Khan, PhD; Kathleen Sobush, MS, MPH; Dana Keener, PhD; Kenneth Goodman, MA; Amy Lowry, MPA; Jakub Kakietek, MPH; Susan Zaro, MPH3
Summary
Approximately two thirds of U.S. adults and one fifth of U.S. children are obese or overweight.
During 1980--2004, obesity prevalence among U.S. adults doubled, and recent data indicate an estimated 33% of U.S. adults are overweight (body mass index [BMI] 25.0--29.9), 34% are obese (BMI ≥30.0), including nearly 6% who are extremely obese (BMI ≥40.0).
The prevalence of being overweight among children and adolescents increased substantially during 1999--2004, and approximately 17% of U.S. children and adolescents are overweight (defined as at or above the 95% percentile of the sex-specific BMI for age growth charts).
Being either obese or overweight increases the risk for many chronic diseases (e.g., heart disease, type 2 diabetes, certain cancers, and stroke). Reversing the U.S. obesity epidemic requires a comprehensive and coordinated approach that uses policy and environmental change to transform communities into places that support and promote healthy lifestyle choices for all U.S. residents.
Environmental factors (including lack of access to full-service grocery stores, increasing costs of healthy foods and the lower cost of unhealthy foods, and lack of access to safe places to play and exercise) all contribute to the increase in obesity rates by inhibiting or preventing healthy eating and active living behaviors.
Recommended strategies and appropriate measurements are needed to assess the effectiveness of community initiatives to create environments that promote good nutrition and physical activity. To help communities in this effort, CDC initiated the Common Community Measures for Obesity Prevention Project (the Measures Project). The objective of the Measures Project was to identify and recommend a set of strategies and associated measurements that communities and local governments can use to plan and monitor environmental and policy-level changes for obesity prevention.
This report describes the expert panel process that was used to identify 24 recommended strategies for obesity prevention and a suggested measurement for each strategy that communities can use to assess performance and track progress over time.
The 24 strategies are divided into six categories:
1) strategies to promote the availability of affordable healthy food and beverages),
2) strategies to support healthy food and beverage choices,
3) a strategy to encourage breastfeeding,
4) strategies to encourage physical activity or limit sedentary activity among children and youth, 5) strategies to create safe communities that support physical activity, and
6) a strategy to encourage communities to organize for change.
(Edited for length - honest!)
1. Communities Should Increase Availability of Healthier Food and Beverage Choices in Public Service Venues
Overview
Limited availability of healthier food and beverage options can be a barrier to healthy eating and drinking. Healthier food and beverage choices include, but are not limited to, low energy dense foods and beverages with low sugar, fat, and sodium content (11). Schools are a key venue for increasing the availability of healthier foods and beverages for children. Other public service venues positioned to influence the availability of healthier foods include after-school programs, child care centers, community recreational facilities (e.g., parks, playgrounds, and swimming pools), city and county buildings, prisons, and juvenile detention centers. Improving the availability of healthier food and beverage choices (e.g., fruits, vegetables, and water) might increase the consumption of healthier foods.
Evidence
CDC's Community Guide reports insufficient evidence to determine the effectiveness of multicomponent school-based nutrition initiatives designed to increase fruit and vegetable intake and decrease fat and saturated fat intake among school-aged children (22,23). However, systematic research reviews have reported an association between the availability of fruits and vegetables and increased consumption (24,25). Farm-to-school salad bar programs, which deliver produce from local farms to schools, have been shown to increase fruit and vegetable consumption among students (12). A 2-year randomized control trial of a school-based environmental intervention that increased the availability of lower-fat foods in cafeteria à la carte areas indicated that sales of lower-fat foods increased among adolescents attending schools exposed to the intervention (26).
2. Communities Should Improve Availability of Affordable Healthier Food and Beverage Choices in Public Service Venues
Overview
Healthier foods generally are more expensive than less-healthy foods (28), which can pose a significant barrier to purchasing and consuming healthier foods, particularly for low-income consumers. Healthier foods and beverages include, but are not limited to, foods and beverages with low energy density and low calorie, sugar, fat, and sodium content (11). Healthier food and beverage choices need to be both available and affordable for persons to consume them.
Strategies to improve the affordability of healthier foods and beverages include lowering prices of healthier foods and beverages and providing discount coupons, vouchers redeemable for healthier foods, and bonuses tied to the purchase of healthier foods. Pricing strategies create incentives for purchasing and consuming healthier foods and beverages by lowering the prices of such items relative to less healthy foods. Pricing strategies that can be applied in public service venues (e.g., schools and recreation centers) include, but are not limited to, decreasing the prices of healthier foods sold in vending machines and in cafeterias and increasing the price of less healthy foods and beverages at concession stands.
Evidence
Research has demonstrated that reducing the cost of healthier foods increases the purchase of healthier foods (29,30). For example, one study indicated that sales of fruits and carrots in high-school cafeterias increased after prices were reduced (31). In addition, interventions that reduced the price of healthier, low-fat snacks in vending machines in school and work settings have been demonstrated to increase purchasing of healthier snacks (32,33). A recent study estimated that a subsidized 10% price reduction on fruits and vegetables would encourage low-income persons to increase their daily consumption of fruits from 0.96 cup to 0.98--1.01 cups and increase their daily consumption of vegetables from 1.43 cups to 1.46--1.50 cups, compared with the recommended 1.80 cups of fruits and 2.60 cups of vegetables (34).
Furthermore, interventions that provide coupons redeemable for healthier foods and bonuses tied to the purchase of healthier foods increase purchase and consumption of healthier foods in diverse populations, including university students, recipients of services from the Supplemental Nutrition Program for Women, Infants, and Children (WIC), and low-income seniors (35--37). For example, one community-based intervention indicated that WIC recipients who received weekly $10 vouchers for fresh produce increased their consumption of fruits and vegetables compared with a control group and sustained the increase 6 months after the intervention (38).
3. Communities Should Improve Geographic Availability of Supermarkets in Underserved Areas
Overview
Supermarkets and full-service grocery stores have a larger selection of healthy food (e.g., fruits and vegetables) at lower prices compared with smaller grocery stores and convenience stores. However, research suggests that low-income, minority, and rural communities have fewer supermarkets as compared with more affluent areas (39,40). Increasing the number of supermarkets in areas where they are unavailable or where availability is limited is might increase access to healthy foods, particularly for economically disadvantaged populations.
Evidence
Greater access to nearby supermarkets is associated with healthier eating behaviors (39). For example, a cross-sectional study of approximately 10,000 participants indicated that blacks living in neighborhoods with at least one supermarket were more likely to consume the recommended amount of fruits and vegetables than blacks living in neighborhoods without supermarkets. Further, blacks consumed 32% more fruits and vegetables for each additional supermarket located in their census tract (41). Another study indicated that increasing the number of supermarkets in underserved neighbors increased real estate values, increased economic activity and employment, and resulted in lower food prices (42).
One cross-sectional study linked height and weight data from approximately 70,000 adolescents to data on food store availability (43). The results indicated that, after controlling for socioeconomic status, greater availability of supermarkets was associated with lower adolescent BMI scores and that a higher prevalence of convenience stores was related to higher BMI among students. The association between supermarket availability and weight was stronger for black students and for students whose mothers worked full-time (43).
4. Communities Should Provide Incentives to Food Retailers to Locate in and/or Offer Healthier Food and Beverage Choices in Underserved Areas
Overview
Healthier foods and beverages include but are not limited to foods and beverages with low energy density and low calorie, sugar, fat, and sodium content as defined by IOM (11). Disparities in the availability of healthier foods and beverages between communities with different income levels, ethnic composition, and other characteristics are well documented, and limited availability of healthier food and beverage choices in underserved communities constitutes a substantial barrier to improving nutrition and preventing obesity (41).
To address this issue, communities can provide incentives to food retailers (e.g., supermarkets, grocery stores, convenience and corner stores, and street vendors) to offer a greater variety of healthier food and beverage choices in underserved areas. Such incentives, both financial and nonfinancial, can be offered to encourage opening new retail outlets in areas with limited shopping options, and existing corner and convenience stores (which typically depend on sales of alcohol, tobacco, and sugar-sweetened beverages) into neighborhood groceries selling healthier foods (44). Financial incentives include but are not limited to tax benefits and discounts, loans, loan guarantees, and grants to cover start-up and investment costs (e.g., improving refrigeration and warehouse capacity). Nonfinancial incentives include supportive zoning, and increasing the capacity of small businesses through technical assistance in starting up and maintaining sales of healthier foods and beverages.
Evidence
The presence of retail venues that provide healthier foods and beverages is associated with better nutrition. Cross-sectional studies indicate that the presence of retail venues offering healthier food and beverage choices is associated with increased consumption of fruits and vegetables and lower BMI (45). One study indicated that every additional supermarket within a given census tract was associated with a 32% increase in the amount of fruits and vegetables consumed by persons living in that census tract (40). Another study indicated that greater availability of supermarkets was associated with lower adolescent BMI scores and a higher prevalence of convenience stores was related to higher BMI among students (43). The association between supermarket availability and weight was stronger for black students compared with white and Hispanic students, and stronger for students whose mothers work full-time compared with those whose mothers work part-time or do not work (43).
5. Communities Should Improve Availability of Mechanisms for Purchasing Foods from Farms
Overview
Mechanisms for purchasing food directly from farms include farmers' markets, farm stands, community-supported agriculture, "pick your own," and farm-to-school initiatives. Experts suggest that these mechanisms have the potential to increase opportunities to consume healthier foods, such as fresh fruits and vegetables, by possibly reducing costs of fresh foods through direct sales; making fresh foods available in areas without supermarkets; and harvesting fruits and vegetables at ripeness rather than at a time conducive to shipping, which might improve their nutritional value and taste (M. Hamm, PhD, Michigan State University, personal communication, 2008).
Evidence
Evidence supporting a direct link between purchasing foods from farms and improved diet is limited. Two studies of initiatives to encourage participation in the Seniors Farmers' Market Nutrition Program (46) and the WIC Farmers' Market Nutrition Program (47) report either increased intention to eat more fruits and vegetables or increased utilization of the program; however, neither study reported direct evidence that the programs resulted in increased consumption of fruits and vegetables. The Farmers' Market Salad Bar Program in the Santa Monica--Malibu Unified School District aims to increase students' consumption of fresh fruits and vegetables and to support local farmers by purchasing produce directly from local farmers' markets and serving them in the district's school lunch program. An evaluation of the program over a 2-year period demonstrated that 30%--50% of students chose the salad bar on any given day (48). Access to farm foods varies between agricultural and metropolitan areas.
6. Communities Should Provide Incentives for the Production, Distribution, and Procurement of Foods from Local Farms
Overview
Currently the United States is not producing enough fruits, vegetables, whole grains, and dairy products for all U.S. citizens to eat the quantities of these foods recommended by the USDA Dietary Guidelines for Americans (27,49). Providing incentives to encourage the production, distribution, and procurement of food from local farms aims might increase the availability and consumption of locally produced foods by community residents, enhance the ability of the food system to provide sufficient quantities of healthier foods, and increase the viability of local farms and food security for communities (M. Hamm, PhD, Michigan State University, personal communication, 2008). Definitions of "local" vary by place and context but may include the area of the foodshed (i.e. a geographic area that supplies a population center with food), food grown within a day's driving distance of the place of sale, or a smaller area such as a city and its surroundings. Incentives to encourage local food production can include forming grower cooperatives, instituting revolving loan funds, and building markets for local farm products through economic development and through collaborations with the Cooperative Extension Service (50). Additional incentives include but are not limited to farmland preservation, marketing of local crops, zoning variances, subsidies, streamlined license and permit processes, and the provision of technical assistance.
Evidence
Evidence suggests that dispersing agricultural production in local areas around the country (e.g., through local farms and urban agriculture) would increase the amount of produce that could be grown and made available to local consumers, improve economic development at the local level (51,52), and contribute to environmental sustainability (53). Although no evidence has been published to link local food production and health outcomes, a study has been funded to explore the potential nutritional and health benefits of eating locally grown foods (A. Ammerman, DrPH, University of North Carolina Center for Health Promotion and Disease Prevention, personal communication, 2009).
7. Communities Should Restrict Availability of Less Healthy Foods and Beverages in Public Service Venues
Overview
Less healthy foods and beverages include foods and beverages with a high calorie, fat, sugar, and sodium content, and a low nutrient content. Less healthy foods are more available than healthier foods in U.S. schools (54). The availability of less healthy foods in schools is inversely associated with fruit and vegetable consumption and is positively associated with fat intake among students (55). Therefore, restricting access to unhealthy food options is one component of a comprehensive plan for better nutrition.
Schools can restrict the availability of less healthy foods by setting standards for the types of foods sold, restricting access to vending machines, banning snack foods and food as rewards in classrooms, prohibiting food sales at certain times of the school day, or changing the locations where unhealthy competitive foods are sold. Other public service venues that could also restrict the availability of less healthy foods include after-school programs, regulated child care centers, community recreational facilities (e.g., parks, recreation centers, playgrounds, and swimming pools), city and county buildings, and prisons and juvenile detention centers.
Evidence
No peer-reviewed studies were identified that examined the impact of interventions designed to restrict the availability of less healthy foods in public service venues. Federal nutritional guidelines prohibit the sale of foods of "minimal nutritional value" in school cafeterias while meals are being served. However, the guidelines currently do not prevent or restrict the sale of these foods in vending machines near the cafeteria or in other school locations (11). Certain states and school districts have developed more restrictive policies regarding competitive foods; 21 states have policies that restrict the sale of competitive foods beyond USDA regulations (56). However, no studies were identified that examined the impact of the policies in those states on student eating behavior.
8. Communities Should Institute Smaller Portion Size Options in Public Service Venues
Overview
Portion size can be defined as the amount (e.g. weight, calorie content, or volume) of a single food item served in a single eating occasion (e.g. a meal or a snack), such as the amount offered to a person in a restaurant, in the packaging of prepared foods, or the amount a person chooses to put on his or her plate (23). Controlling portion size is important because research has demonstrated that persons often either 1) do not notice differences in portion sizes and unknowingly eat larger amounts when presented with a larger portion or 2) when eating larger portions, do not consume fewer calories at subsequent meals or during the rest of the day (57).
Evidence
Evidence is lacking to demonstrate the effectiveness of population-based interventions aimed at reducing portion sizes in public service venues. However, evidence from clinical studies conducted in laboratory settings demonstrates that decreasing portion size decreases energy intake (58--60). This finding holds across a wide variety of foods and different types of portions (e.g., portions served on a plate, sandwiches, or prepackaged foods such as potato chips). Clinical studies conducted in nonlaboratory settings demonstrate that increased portion size leads to increased energy intake (61,62). The majority of studies that evaluated the impact of portion size on nutritional outcomes were short term, producing little evidence regarding the long-term impact of portion size on eating patterns, nutrition, and obesity (23). Intervention studies are underway that evaluate the impact of limiting portion size, combined with other strategies to prevent obesity in workplaces (63).
9. Communities Should Limit Advertisements of Less Healthy Foods and Beverages
Overview
Research has demonstrated that more than half of television advertisements viewed by children and adolescents are food-related; the majority of them promote fast foods, snack foods, sweets, sugar-sweetened beverage products, and other less healthy foods that are easily purchased by youths (11). In 2006, major food and beverage marketers spent $1.6 billion to promote food and beverage products among children and adolescents in the United States (64). Television advertising has been determined to influence children to prefer and request high-calorie and low-nutrient foods and beverages and influences short-term consumption among children aged 2--11 years (65). Therefore, limiting advertisements of less healthy foods might decrease the purchase and consumption of such products. Legislation to limit advertising of less healthy foods and beverages usually is introduced at the federal or state level. However, local governing bodies, such as district level school boards, might have the authority to limit advertisements of less healthy foods and beverages in areas within their jurisdiction (9).
Evidence
Little evidence is available regarding the impact of restricting advertising on purchasing and consumption of less healthy foods (11,22,66,67). However, cross-sectional time-series studies of tobacco-control efforts suggest that an association exists between advertising bans and decreased tobacco consumption (22,68). One study estimated that a ban on fast-food advertising on children's television programs could reduce the number of overweight children aged 3--11 years by 18% and the number of overweight adolescents aged 12--18 years by 14% (69). Limited bans of advertising, which include some media but not others (e.g., television but not newspapers), might have little or no effect as the food and beverage industry might redirect its advertising efforts to media not included in the ban, thus limiting researchers' ability to detect causal effects (68).
10. Communities Should Discourage Consumption of Sugar-Sweetened Beverages
Overview
Consumption of sugar-sweetened beverages (e.g., carbonated soft drinks, sports drinks, flavored sweetened milk, and fruit drinks) among children and adolescents has increased dramatically since the 1970s and is associated with higher daily caloric intake and greater risk of obesity (70). Although consumption of sugar-sweetened beverages occurs most often in the home, schools and child care centers also contribute to the problem either by serving sugar-sweetened beverages or by allowing children to purchase sugar-sweetened beverages from vending machines (70). Policies that restrict the availability of sugar-sweetened beverages and 100% fruit juice in schools and child care centers might discourage the consumption of high-caloric beverages among children and adolescents.
Evidence
One longitudinal study of a school-based environmental intervention conducted among Native American high school students that combined education to decrease the consumption of sugar-sweetened beverages and increase knowledge of diabetes risk factors with the development of a youth-oriented fitness center demonstrated a substantial reduction in consumption of sugar-sweetened beverages for a 3-year period (71). A randomized control study of a home-based environmental intervention that eliminated sugar-sweetened beverages from the homes of a diverse group of adolescents demonstrated that, among heavier adolescents, the intervention resulted in significantly (p = 0.03) greater reduction in BMI scores compared with the control group (72).
11. Communities Should Increase Support for Breastfeeding
Overview
Exclusive breastfeeding is recommended for the first 4--6 months of life, and breastfeeding together with the age-appropriate introduction of complementary foods is encouraged for the first year of life. Epidemiologic data suggest that breastfeeding provides a limited degree of protection against childhood obesity, although the reasons for this association are not clear (11). Breastfeeding is thought to promote an infant's ability to self regulate energy intake, thereby allowing him or her to eat in response to internal hunger and satiety cues (73). Some research suggests that the metabolic/hormonal cues provided by breastmilk contribute to the protective association between breastfeeding and childhood obesity (74). Despite the many advantages of breastfeeding, many women choose to bottle-feed their babies for a variety of reasons, including social and structural barriers to breastfeeding, such as attitudes and policies regarding breastfeeding in health-care settings and public and work places (75).
Breastfeeding support programs aim to increase the initiation and exclusivity rate of breastfeeding and to extend the duration of breastfeeding. Such programs include a variety of interventions in hospitals and workplaces (e.g., setting up breastfeeding facilities, creating a flexible work environment that allows breastfed infants to be brought to work, providing onsite child care services, and providing paid maternity leaves), and maternity care (e.g., polices and staff training programs that promote early breastfeeding initiation, restricting the availability of supplements or pacifiers, and providing facilities that accommodate mothers and babies). The CDC Guide to Breastfeeding Interventions identifies the following general areas of interventions and programs as effective in supporting breastfeeding: 1) maternity care practices, 2) support for breastfeeding in the workplace, 3) peer support, 4) educating mothers, 5) professional support, and 6) media and community-wide campaigns (76).
Evidence
Evidence directly linking environmental interventions that support breastfeeding with obesity-related outcomes is lacking. However, systematic reviews of epidemiologic studies indicate that breastfeeding helps prevent pediatric obesity: breastfed infants were 13%--22% less likely to be obese than formula-fed infants (77,78), and each additional month of breastfeeding was associated with a 4% decrease in the risk of obesity (79). Furthermore, one study demonstrated that infants fed with low (<20%>80% of feedings from breastmilk) (80).
Systematic reviews indicate that support programs in health-care settings are effective in increasing rates of breastfeeding initiation and in preventing early cessation of breastfeeding. Training medical personnel and lay volunteers to promote breastfeeding decreases the risk for early cessation of breastfeeding by 10% (81) and that education programs increase the likelihood of the initiation of breastfeeding among low-income women in the United States by approximately twofold (75).
One systematic review did not identify any randomized control trials that have tested the effectiveness of workplace-wide interventions promoting breastfeeding among women returning to paid employment (82). However, one study demonstrated that women who directly breastfed their infant at work and/or pumped breast milk at work breastfed at a higher intensity than women who did not breastfeed or pump breast milk at work (83). Furthermore, evaluations of individual interventions aimed at supporting breastfeeding in the workplace demonstrate increased initiation rates and duration of breastfeeding compared with national averages (76).
12. Communities Should Require Physical Education in Schools
Overview
This strategy supports the Healthy People 2010 objective (objective no. 22.8) to increase the proportion of the nation's public and private schools that require daily PE for all students (15). The National Association for Sport and Physical Education (NASPE) and the American Heart Association (AHA) recommend that all elementary school students should participate in >150 minutes per week of PE and that all middle and high school students should participate in >225 minutes of PE per week for the entire school year (84). School-based PE increases students' level of physical activity and improves physical fitness (23).
Many states mandate some level of PE in schools: 36 states mandate PE for elementary-school students, 33 states mandate PE for middle-school students, and 42 states mandate PE for high-school students (84). However, to what extent these requirements are enforced is unclear, and only two states (Louisiana and New Jersey) mandate the recommended >150 minutes per week of PE classes. Potential barriers to implementing PE classes in schools include concerns among school administrators that PE classes compete with traditional academic curricula or might detract from students' academic performance. However, a Community Guide review identified no evidence that time spent in PE classes harms academic performance (23).
Evidence
In a systematic review of 14 studies, the Community Guide demonstrated that school-based PE was effective in increasing levels of physical activity and improving physical fitness (23). The review included studies of interventions that increased the amount of time spent in PE classes, the amount of time students are active during PE classes, or the amount of moderate or vigorous physical activity (MVPA) students engage in during PE classes.
Most studies that correlated school-based PE classes and the physical activity and fitness of students focused on the quality and duration of PE classes (e.g., the amount of physical activity during class, the amount of MVPA) rather than simply whether PE was required. However, requiring that PE classes be taught in schools is a necessary minimum condition for measuring the effectiveness of efforts to improve school-based PE class curricula.
13. Communities Should Increase the Amount of Physical Activity in PE Programs in Schools
Overview
Time spent in PE classes does not necessarily mean that students are physically active during that time. Increasing the amount of physical activity in school-based PE classes has been demonstrated to be effective in increasing fitness among children. Specifically, increasing the amount of time children are physically active in class, increasing the number of children moving as part of a game or activity (e.g., by modifying game rules so that more students are moving at any given time, or by changing activities to those where all participants stay active), and increasing the amount of moderate to vigorous activity during class time are effective strategies for increasing physical activity.
Evidence
In a review of 14 studies, the Community Guide demonstrated strong evidence of effectiveness for enhancing PE classes taught in school by increasing the amount of time students spend in PE class, the amount of time they are active during PE classes, or the amount of MVPA they engage in during PE classes (23). The median effect of modifying school PE curricula as recommended was an 8% increase in aerobic fitness among school-aged children. Modifying school PE curricula was effective in increasing physical activity across racial, ethnic, and socioeconomic populations, among males and females, in elementary and high schools, and in urban and rural settings.
A quasi-experimental study of the Sports, Play, and Active Recreation for Kids (SPARK) school PE program, which is designed to maximize participation in physical activity during PE classes, demonstrated that the program increased physical activity during PE classes but the effect did not carry over outside of school (85). The study identified no significant effects on fitness levels among boys (p = 29--55), but girls in the classes led by a PE specialist were superior in abdominal and cardio respiratory endurance to girls in the control condition (p = 0.03). The Child and Adolescent Trial for Cardiovascular Health (CATCH) is another intervention which aims to increase MVPA in children during PE classes. A randomized, controlled field trail of CATCH that was conducted with more than 5,000 third-grade students from 96 public schools over a 3-year period indicated that the intensity of physical activity in PE classes (class time devoted to MVPA) during the intervention increased significantly in the intervention schools compared with the control schools (p<0.02) (86).
The background and training of teachers who deliver PE curricula might mediate the effect of interventions on physical activity. For example, one study indicated that SPARK classes led by PE specialists spent more time per week in physical activity (40 minutes) than classes led by regular teachers who had received training in the curriculum (33 minutes) (85).
14. Communities Should Increase Opportunities for Extracurricular Physical Activity
Overview
Opportunities for extracurricular physical activity outside of school hours to complement formal PE increasingly are an important strategy to prevent obesity in children and youth (11). This strategy focuses on noncompetitive physical activity opportunities such as games and dance classes available through community and after-school programs, and excludes participation in varsity team sports or sport clubs, which require tryouts and are not open to all students. Research has demonstrated that after-school programs that provide opportunities for extracurricular physical activity increase children's level of physical activity and improve other obesity-related outcomes.
Evidence
Intervention studies have demonstrated that participation in after-school programs that provided opportunities for extracurricular physical activity held both at schools and other community settings increased participants' level of physical activity (87,88) and improved obesity-related outcomes, such as improved cardiovascular fitness and reduced body fat content (89). Two pilot studies demonstrated that providing opportunities for extracurricular physical activity increased levels of physical activity (90) and decreased sedentary behavior (91) among participants.
The Promoting Life Activity in Youth (PLAY) program is designed to teach active lifestyle habits to children and help them to accumulate 30--60 minutes of moderate to vigorous physical activity per day. One study indicated that participation in PLAY and PE had a significant impact on physical activity among girls (p<0.001) but not for boys (90). Lack of access is a barrier that might limit the impact of increased availability of opportunities for extracurricular physical activity. In East Palo Alto, California, where the city provided buses from schools to the community center, 70% of the eligible girls attended dance classes at least 2 days a week. In Oakland, where the city did not provide buses, only 33% of eligible girls attended the class two or more times a week (91).
15. Communities Should Reduce Screen Time in Public Service Venues
Overview
Mechanisms linking extended screen viewing time and obesity include displacement of physical activity; a reduction in metabolic rate and excess energy intake; and increased consumption of food advertised on television as a result of exposure to marketing of high energy dense foods and beverages (92,93). The American Academy of Pediatrics (94) recommends that parents limit children's television time to no more than to 2 hours per day. Although only a relatively small portion of television viewing and computer and video game use occurs in public service venues such as schools, day care centers, and after-school programs, local policymakers can intervene to limit screen viewing time among children and youth in these venues.
Evidence
Long-term cohort studies have demonstrated a positive significant (p = 0.02) association between television viewing in childhood and body mass index levels in adulthood (92,93). In addition, a cross-sectional study indicated that the amount of time spent watching TV/video was significantly related to overweight among low-income preschool children (p<0.004) (95). A randomized controlled school-based trial indicated that children who reduced their television, videotape, and video game use had significant decreases in BMI (p = 0.002), tricep skin fold thickness (p = 0.002), and waist circumference (p<0.001) compared with children in control groups (96). The evidence surrounding children's television viewing and its relationship to physical activity has been somewhat inconsistent. A review evaluating correlates of childhood physical activity determined that some studies find time spent engaged in sedentary activities, specifically TV viewing and video use, has a negative association to physical activity, while other studies find no relationship (97). Multicomponent school-based intervention studies have demonstrated that spending less time watching television is associated with increased physical activity (98) and decreased risk of childhood obesity among girls but not boys (99).
16. Communities Should Improve Access to Outdoor Recreational Facilities
Overview
Recreation facilities provide space for community members to engage in physical activity and include places such as parks and green space, outdoor sports fields and facilities, walking and biking trails, public pools, and community playgrounds. Accessibility of recreation facilities depends on a number of factors such as proximity to homes or schools, cost, hours of operation, and ease of access. Improving access to recreation facilities and places might increase physical activity among children and adolescents.
Evidence
In a review based on 10 studies, the Community Guide concluded that efforts to increase access to places for physical activity, when combined with informational outreach, can be effective in increasing physical activity (100). The studies reviewed by the Community Guide included interventions such as creating walking trails, building exercise facilities, and providing access to existing facilities. However, it was not possible to separate the benefits of improved access to places for physical activity from health education and services that were provided concurrently (100).
A comprehensive review of 108 studies indicated that access to facilities and programs for recreation near their homes, and time spent outdoors, correlated positively with increased physical activity among children and adolescents (97). A study that analyzed data from a longitudinal survey of 17,766 adolescents indicated that those who used community recreation centers were significantly more likely to engage in moderate to vigorous physical activity (p≤0.00001) (101).
A multivariate analysis indicated that self-reported access to a park, and the perception that footpaths are safe for walking were significantly associated with adult respondents being classified as physically active at a level sufficient for health benefits (102). Another study that used self-report and GIS data concluded that longer distances and the presence of barriers (e.g., busy streets and steep hills) between individuals and bike paths were associated with non-use of bike paths (103).
17. Communities Should Enhance Infrastructure Supporting Bicycling
Overview
Enhancing infrastructure supporting bicycling includes creating bike lanes, shared-use paths, and routes on existing and new roads; and providing bike racks in the vicinity of commercial and other public spaces. Improving bicycling infrastructure can be effective in increasing frequency of cycling for utilitarian purposes (e.g., commuting to work and school, bicycling for errands). Research demonstrates a strong association between bicycling infrastructure and frequency of bicycling.
Evidence
Longitudinal intervention studies have demonstrated that improving bicycling infrastructure is associated with increased frequency of bicycling (104,105). Cross-sectional studies indicated a significant association between bicycling infrastructure and frequency of biking (p<0.001) (103,106,107).
18. Communities Should Enhance Infrastructure Supporting Walking
Overview
Infrastructure that supports walking includes but is not limited to sidewalks, footpaths, walking trails, and pedestrian crossings. Walking is a regular, moderate-intensity physical activity in which relatively large numbers of persons can engage. Well-developed infrastructure supporting walking is an important element of the built environment and has been demonstrated to be associated with physical activity in adults and children. Interventions aimed at supporting infrastructure for walking are included in street-scale urban design and land use interventions that support physical activity in small geographic areas. These interventions can include improved street lighting, infrastructure projects to increase the safety of street crossings, use of traffic calming approaches (e.g., speed humps and traffic circles), and enhancing street landscaping (108).
Evidence
The Community Guide reports sufficient evidence that street-scale urban design and land use policies that support walking are effective in increasing levels of physical activity (108). Reviews of cross-sectional studies of environmental correlates of physical activity and walking generally find a positive association between infrastructure supportive of walking and physical activity (109,110). However, some systematic reviews indicated no evidence of an association between the presence of sidewalks and physical activity (111). Other reviews indicated associations, but only for certain subgroups of subjects (e.g., men and users of longer walking trails) (108,109). Intervention studies demonstrate effectiveness of enhanced walking infrastructure when combined with other strategies. For example, evaluation of the Marin County Safe Routes to School program indicated that identifying and creating safe routes to school, together with educational components, increased the number of students walking to school (105). When considering the evidence for this strategy, planners should note that physically active individuals might be more likely to locate in communities that have an existing infrastructure for walking, which might produce spurious correlations in cross-sectional studies (109).
19. Communities Should Support Locating Schools within Easy Walking Distance of Residential Areas
Overview
Walking to and from school has been demonstrated to increase physical activity among children during the commute, leading to increased energy expenditure and potentially to reduced obesity. However, the percentage of students walking to school has dropped dramatically over the past 40 years, partially due to the increased distance between children's homes and schools. Current land use trends and policies pose barriers to building smaller schools located near residential areas. Therefore, requisite activities that support locating schools within easy walking distance of residential areas include efforts to change land use and school system policies.
Evidence
The Community Guide indicated that community-scale urban design and land use policies and practices, including locating schools, stores, workplaces, and recreation areas close to residential areas, are effective in facilitating an increase in levels of physical activity (23,108). A simulation modeling study conducted by the U.S. Environmental Protection Agency (EPA) in Florida indicated that school location as well as the quality of the built environment between home and school has an effect on walking and biking to school. Specifically, this combination of school location and built environment quality would produce a 13% increase in nonmotorized travel to school (112). A cross-sectional study in the Philippines indicated that adolescents who walked to school expended significantly more energy than those who used motorized modes of transport. This association was not explainable by in-school or after-school sports or exercise. Assuming no change takes place in energy intake, the difference in energy expenditure between transport modes would lead to an expected 2--3-pound annual weight gain by youth who commute to school by motorized transport (113).
As a result of current land use trends and policies regarding school siting, very little work has been done to locate schools within neighborhoods. A study conducted by the Environmental Protection Agency suggests that the trend of building larger schools with larger catchment areas should be reversed to locate schools within neighborhoods (112). The distance between homes and schools is not the only factor that affects whether children walk to and from school. Among students living within 1 mile of school, the percentage of walkers fell from 90% to 31% between 1969 and 2001 (112). The decrease in walking to and from school has been attributed to a poor walking environment, defined as a built environment that has low population densities, little mixing of land uses, long blocks, and incomplete sidewalks (112). The majority of efforts to encourage walking to and from school involve improving the routes (e.g., Marin County's Safe Routes to School program) rather than improving the location of schools. Previous studies have recommended that local governments and school districts should ensure that children and youth have safe walking and bicycling routes between their homes and schools and encouraged their use (11).
20. Communities Should Improve Access to Public Transportation
Overview
Public transportation includes mass transit systems such as buses, light rail, street cars, commuter trains, and subways, and the infrastructure supporting these systems (e.g., transit stops and dedicated bus lanes). Improving access to public transportation encourages the use of public transit, which might, in turn, increase the level of physical activity when transit users walk or ride bicycles to and from transit access points.
Evidence
The Community Guide identified insufficient evidence to determine the effectiveness of transportation and travel policies and practices in increasing the level of physical activity or improving fitness because only one study of adequate quality was available (108). In a study that analyzed data from the 2001 National Household Travel Survey, researchers indicated that 29% of individuals who walk to and from public transit achieve at least 30 minutes of daily physical activity (114). Another study indicated that access to public transit was associated with decreases in the odds of using automobiles as a preferred mode of transportation and increases in the odds of walking and/or bicycling (115). In a cross-sectional study carried out in four San Francisco neighborhoods, researchers indicated that individuals with easy access to the Bay Area Rapid Transit System (BART) made, on average, 0.66 more nonmotorized trips than those who did not have access to BART (116).
Physically active individuals might be more likely to locate into communities with an infrastructure that supports physical activity, including neighborhoods with infrastructure supporting public transportation (110). Most neighborhood-level cross-sectional studies do not control for individual-level characteristics (e.g., ethnicity, age, socioeconomic status). Environmental factors, including infrastructure for public transit, also might affect different subpopulations differently (110,116).
21. Communities Should Zone for Mixed-Use Development
Overview
Zoning for mixed-use development is one type of community-scale land use policy and practice that allows residential, commercial, institutional, and other public land uses to be located in close proximity to one another. Mixed-use development decreases the distance between destinations (e.g., home and shopping), which has been demonstrated to decrease the number of trips persons make by automobile and increase the number of trips persons make on foot or by bicycle. Zoning regulations that accommodate mixed land use could increase physical activity by encouraging walking and bicycling trips for nonrecreational purposes. Zoning laws restricting the mixing of residential and nonresidential uses and encouraging single-use development can be a barrier to physical activity.
Evidence
The Community Guide lists mixed-use development and diversity of residential and commercial developments as examples of community-scale urban design and land use policies and practices (23). The Community Guide rated the evidence for community-scale urban design and land use policies and practices as sufficient to justify a recommendation that these characteristics increase physical activity (23,108). The recommendation was based on a review of 12 studies in which the median improvement in some aspect of physical activity was 161% (23,108).
Studies using correlation analyses and regression models indicated that mixed land use was associated with increased walking and cycling (110,117--119). A review of quasi-experimental studies indicated residents from high walkability neighborhoods (defined by higher density, greater connectivity, and more land use mix) reported twice as many walking trips per week than residents from low walkability neighborhoods (defined by low density, poor connectivity, and single land uses) (110). A cross-sectional study conducted in Atlanta, GA indicated that odds of obesity declined as mixed land use increased (118).
Some increased level of physical activity among residents of mixed-use neighborhoods might be attributable to selection of these types of neighborhoods by persons more likely to engage in physical activity (119). Mixed-use development is often combined with multiple design elements from urban planning and policy, including density, connectivity, roadway design, and walkability.
22. Communities Should Enhance Personal Safety in Areas Where Persons Are or Could Be Physically Active
Overview
Personal safety is affected by crime rates and other nontraffic-related hazards that exist in communities. Limited but supportive evidence indicates that improving community safety might be effective at increasing levels of physical activity in adults and children. In addition, safety considerations affect parents' decisions to allow their children to play and walk outside (11). Interventions to improve safety, such as increasing police presence, decreasing the number of abandoned buildings and homes, and improving street lighting, can be undertaken by individual communities.
Evidence
Cross-sectional studies have demonstrated a negative relationship between crime rates and/or perceived safety and physical activity in neighborhoods, particularly among adolescents (101,120,121). A systematic review indicated that observational measurements of safety (e.g., crime incidence) were negatively associated with physical activity, but subjective measurements (self-reported safety) were not correlated with physical activity (120).
Few intervention studies have evaluated the impact of policies and practices to improve personal safety on physical activity. However, one study indicated that improved street lighting in London led to reduced crime rates, less fear of crime, and more pedestrian street use (122). Some studies suggest that the relationship between safety and physical activity might vary by gender and/or other individual-level characteristics. For example, one study indicated that incidence rates of violent crimes were associated with lower physical activity in adolescent girls, but not in boys (121).
Persons of lower socioeconomic status depend more on walking as a means of transportation as compared with those of higher socioeconomic status, and they also are more likely to live in neighborhoods that are unsafe (11). This could explain why some studies do not find a positive association between perceived safety and physical activity. Reducing crime levels might require complex, multisectoral, and long-term efforts, which might go beyond the authority and capacity of local communities.
23. Communities Should Enhance Traffic Safety in Areas Where Persons Are or Could Be Physically Active
Overview
Traffic safety is the security of pedestrians and bicyclists from motorized traffic. Traffic safety can be enhanced by engineering streets for lower speeds or by retrofitting existing streets with traffic calming measurements (e.g., speed tables and traffic circles). Traffic safety can also be enhanced by developing infrastructure to improve the safety of street crossings (e.g., raised crosswalks and textured pavement) for nonmotorized traffic and for pedestrians.
The lack of safe places to walk, run, and bicycle as a result of real or perceived traffic hazards can deter children and adults from being physically active. Enhancing traffic safety has been demonstrated to be effective in increasing levels of physical activity in adults and children. Research suggests that persons living in neighborhoods with higher traffic safety are more physically active.
Evidence
The Community Guide reviewed both community-scale and street-scale urban design and land use policies and practices, including interventions aimed at improving traffic safety. The review indicated that both community-scale and street-scale policies and practices were effective in increasing physical activity (108). On the basis of sufficient evidence of effectiveness, the Community Guide recommends implementing community-scale and street-scale urban design and land use policies to promote physical activity, including design components to improve street lighting, infrastructure projects to increase safety of pedestrian street crossings, and use of traffic calming approaches such as speed humps and traffic circles (23).
A review of 19 studies examined the effects of environmental factors on physical activity, five of which considered traffic safety (123). One study demonstrated significant effects of traffic safety on increased physical activity (102).
24. Communities Should Participate in Community Coalitions or Partnerships to Address Obesity
Overview
Community coalitions consist of public- and private-sector organizations that, together with individual citizens, work to achieve a shared goal through the coordinated use of resources, leadership, and action (11). Potential stakeholders in community coalitions aimed at obesity prevention include but are not limited to community organizations and leaders, health-care professionals, local and state public health agencies, industries (e.g., building and construction, restaurant, food and beverage, and entertainment), the media, educational institutions, government (including transportation and parks and recreation departments), youth-related and faith-based organizations, nonprofit organizations and foundations, and employers.
The effectiveness of community coalitions stems from the multiple perspectives, talents, and expertise that are brought together to work toward a common goal. In addition, coalitions build a sense of community, enhance residents' engagement in community life, and provide a vehicle for community empowerment. Research in tobacco control demonstrates that the presence of antismoking community coalitions is associated with lower rates of cigarette use. Based on this research, it is plausible that community coalitions might be effective in preventing obesity and in improving physical activity and nutrition.
Evidence
Little evidence is available to determine the impact of community coalitions on obesity prevention (11). However, tobacco-control literature demonstrates that the presence of antismoking community coalitions is associated with lower rates of tobacco consumption. One study indicated that states with a greater number of anti-tobacco coalitions had lower per capita cigarette consumption than states with a lower number of coalitions (124).
Next Steps
The next step for this project is to disseminate the recommended community strategies and suggested measurements for use by local governments and communities throughout the United States. To help accomplish this, an implementation and measurement guide will be published and made available through the CDC website (available at http://www.cdc.gov/nccdphp/dnpao/publications/index.html). In addition, the measurements will be integrated into a new survey module that will be available to all members of ICMA's Center for Performance Measurement. Dissemination of these recommended obesity prevention strategies and proposed measurements is intended to inspire communities to consider implementing new policy and environmental change initiatives aimed at reversing the obesity epidemic. The recommended strategies and suggested measurements outlined in this report are being pilot tested in the Minnesota and Massachusetts state surveillance systems (Laura Hutton, MA, Minnesota Department of Health, personal communication, 2009; Maya Mohan, MPH, Massachusetts Department of Health, personal communication, 2009).
Labels: article, cdc, farmers markets, farming, health, obesity, study
posted by Leslie at
1:36 PM
0 Comments:
Post a Comment
Subscribe to Post Comments [Atom]
<< Home