The Effect of State Competitive Food and Beverage Regulations on Childhood Overweight and Obesity

A scoping review of the role of policy in mitigating childhood obesity in underserved populations using the RE-AIM framework

BACKGROUND

Childhood obesity is an escalating crisis in the United States. Health policy may impact this epidemic which disproportionally affects underserved populations.

AIM

The aim was to use the reach, effectiveness, adoption, implementation, and maintenance (RE-AIM) framework to assess health policy impact on preventing or treating school-aged children (5 > 18 years) with obesity in underserved populations.

METHODS

A scoping review of 842 articles was conducted. Twenty-four articles met the inclusion criteria and underwent data extraction.

RESULTS

Twelve studies included subgroup analysis, with four suggesting an impact of policy on at-risk groups. None of the 24 studies fully applied the RE-AIM framework. Policies positively impacted childhood obesity in 12 studies across the sample.

LINKING EVIDENCE TO ACTION

Our review revealed inconsistent evidence for the effectiveness of policy on childhood obesity, perhaps due to the lack of focus on the social determinants of health. In addition, many studies did not evaluate the outcomes for underserved populations. Therefore, we propose more attention to social determinants in future legislation and evaluation of policy effectiveness on underserved populations. Findings identify an urgent need for the design, implementation, and evaluation of policies specifically directed to address the inequities of racism, social injustices, and social determinants of health that impact childhood obesity in the United States. Future work needs to identify who was reached by the policy, who benefitted from the policy, and how policies were implemented to address obesity-related health disparities. Nurses should advocate for the evaluation of childhood obesity policies, particularly in underserved populations, to determine effectiveness. Nurses, particularly those trained in population and community health and research, should advocate for policy research that considers inequities rather than controls for these variables. Multi-layered interventions can then be tailored to sub-populations and evaluated more effectively.

"Competitive" food and beverage policies and weight status: A systematic review of the evidence among sociodemographic subgroups

Prior studies identified variable associations between competitive food and beverage policies (CF&B) and youth obesity, potentially due to differences across population subgroups. This review summarizes the evidence on associations between CF&B policies and childhood obesity within gender, grade level/ age, race/ethnicity, and/or socioeconomic levels. PubMed, EMBASE, CINAHL, and ERIC database searches identified studies published in English in Canada and the United States between January 1, 2000, and February 28, 2022. Of the 18 selected studies, six were cross-sectional, two correlational, nine were before/after designs, and one study utilized both a cross-sectional and pre-post design. Twelve studies reported findings stratified by a single sociodemographic factor, with grade level/age as the most frequently reported. Although the evidence varied, greater consistency in direction of associations and strengths of evidence were seen among middle school students. Six studies reported findings jointly by multiple sociodemographic subgroups with evidence suggesting CF&B associations with slower rate of increase or plateaus or declines in obesity among multiple subgroups, though the strengths of evidence varied. Over the past two decades, there have been relatively limited subgroup analyses on studies about CF&B policies and childhood obesity. Studies are needed with stronger designs and analyses disaggregated, particularly by race/ethnicities and socioeconomic factors, across places and time.

Heterogeneity in place effects on health: The case of time preferences and adolescent obesity

We leverage a natural experiment in combination with data on adolescents' time preferences to assess whether there is heterogeneity in place effects on adolescent obesity. We exploit the plausibly exogenous assignment of military servicemembers, and consequently their children, to different installations to identify place effects. Adolescents' time preferences are measured by a validated survey scale. Using the obesity rate in the assigned installation county as a summary measure of its obesity-related environments, we show that exposure to counties with higher obesity rates increases the likelihood of obesity among less patient adolescents but not among their more patient counterparts.

Impact of the external school food environment on the associations of internal school food environment with high schoolers’ diet and body mass index

Objective:

To examine associations of school food availability with student intake frequency and BMI, and whether the number of neighborhood food outlets modifies these associations.

Design:

Baseline assessment of a nationally representative cohort study of U.S. 10th graders. Students reported intake frequency of fruits and vegetables (FV), snacks, and soda. BMI was calculated from measured height and weight. Administrators of 72 high schools reported the frequency of school availability of FV, snacks, and soda. The number of food outlets within 1 km and 5 km were linked with geocoded school addresses. Data were analyzed using adjusted linear and logistic mixed models with multiple imputation for missing data.

Setting:

U.S. 2009-2010.

Participants:

2,263 U.S. 10th graders from the Next Generation Health Study (NEXT).

Results:

Greater school FV availability was positively associated with student FV intake. Food outlets within 5 km of schools (but not 1 km) attenuated the association of school FV availability with student intake; this was no longer significant at schools with >58 food outlets within 5 km. School food availability was not associated with student BMI or student snack or soda intake.

Conclusions:

School food availability was associated with student intake of FV, but not with snacks, soda, or BMI. Attenuation of the observed associations by the school neighborhood food environment indicates a need to find ways to support healthy student eating behaviors in neighborhoods with higher food outlet density.

Regional and sociodemographic differences in average BMI among US children in the ECHO program

OBJECTIVE

The aim of this study was to describe the association of individual-level characteristics (sex, race/ethnicity, birth weight, maternal education) with child BMI within each US Census region and variation in child BMI by region.

METHODS

This study used pooled data from 25 prospective cohort studies. Region of residence (Northeast, Midwest, South, West) was based on residential zip codes. Age- and sex-specific BMI z scores were the outcome.

RESULTS

The final sample included 14,313 children with 85,428 BMI measurements, 49% female and 51% non-Hispanic White. Males had a lower average BMI z score compared with females in the Midwest (β = -0.12, 95% CI: -0.19 to -0.05) and West (β = -0.12, 95% CI: -0.20 to -0.04). Compared with non-Hispanic White children, BMI z score was generally higher among children who were Hispanic and Black but not across all regions. Compared with the Northeast, average BMI z score was significantly higher in the Midwest (β = 0.09, 95% CI: 0.05 to 0.14) and lower in the South (β = -0.12, 95% CI: -0.16 to -0.08) and West (β = -0.14, 95% CI: -0.19 to -0.09) after adjustment for age, sex, race/ethnicity, and birth weight.

CONCLUSIONS

Region of residence was associated with child BMI z scores, even after adjustment for sociodemographic characteristics. Understanding regional influences can inform targeted efforts to mitigate BMI-related disparities among children.

The food environment in schools and their immediate vicinities associated with excess weight in adolescence: A systematic review and meta-analysis

AIM

The present study systematically reviewed the characteristics of the food environment in schools and their immediate vicinities associated with excess weight in adolescents.

METHODS

We searched for relevant articles in seven databases. No restrictions were applied on language, publication date, and status of publication. The study selection process and data extraction were conducted by two authors independently. For meta-analyses, the random-effects model and the maximum-likelihood method were applied.

RESULTS

A total of 9327 publications were identified from the initial search. Of these, 20 studies met the inclusion criteria and were included in the systematic review. The sale of food in school or immediate vicinity was associated with high BMI [Odds ratio (OR)= 1.14, 95% confidence interval (CI) 1.01, 2.06]. The availability of healthy food provided by school significantly decreased the odds of obesity [OR= 0.89, 95%CI 0.82, 0.96]. However, the presence of nutrition policies or programs at school was not associated with obesity (OR= 0.81, 95%CI 0.57, 1.16).

CONCLUSIONS

This study highlights the need for improvement in school food environment, including restricting students' exposure to unhealthy foods. The quality of food (healthy vs unhealthy) provided or made available to adolescents in the school food environment influences their weight status. Therefore, promotion of healthy food programs and availability of healthy food at school would limit the prevalence of excess weight in adolescents.

Improving the school food environment for the prevention of childhood obesity: What works and what doesn't

The food environment has a significant influence on dietary choices, and interventions designed to modify the food environment could contribute to the prevention of childhood obesity. Many interventions have been implemented at the school level, but effectiveness in addressing childhood obesity remains unclear. We undertook a systematic review, a meta-analysis, and meta-regression analyses to assess the effectiveness of interventions on the food environment within and around schools to improve dietary intake and prevent childhood obesity. Estimates were pooled in a random-effects meta-analysis with stratification by anthropometric or dietary intake outcome. Risk of bias was formally assessed. One hundred papers were included. Interventions had a significant and meaningful effect on adiposity (body mass index [BMI] z score, standard mean difference: -0.12, 95% confidence interval: 0.15, 0.10) and fruit consumption (portions per day, standard mean difference: +0.19, 95% confidence interval: 0.16, 0.22) but not on vegetable intake. Risk of bias assessment indicated that n = 43 (81%) of non-randomized controlled studies presented a high risk of bias in the study design by not accounting for a control. Attrition bias (n = 34, 79%) and low protection of potential contamination (n = 41, 95%) presented the highest risk of bias for randomized controlled trials. Changes in the school food environment could improve children's dietary behavior and BMI, but policy actions are needed to improve surrounding school food environments to sustain healthy dietary intake and BMI.

Association between Nutrition Policies and Student Body Mass Index

In response to concerns about childhood obesity, many US states have implemented policies to limit the sale of unhealthy foods and beverages (e.g., snacks, desserts, and sugary drinks) sold in competition with school meal programs (i.e., competitive foods) in order to improve the nutritional environment of schools and support student health. This study measured state-level competitive food and beverage policies that require foods and beverages sold in à la carte lines, vending machines, and school stores to meet strong nutrition standards and tested the hypothesis that students living in states with stronger laws would have lower body mass index (BMI)-for-age percentiles. BMI data from a national sample of 1625 students attending 284 schools from the School Nutrition and Meal Cost Study were linked to state laws coded as part of the National Wellness Policy Study. A survey-adjusted linear regression model accounting for student and school-level characteristics showed that stronger state nutrition policies were associated with lower student BMI scores (coefficient: -0.06, 95% CI: -0.12, -0.00). Additional models indicated that stronger state policies were significantly associated with fewer unhealthy foods and beverages available in schools. These findings suggest that strong regulations on competitive foods and beverages may lead to improvements in the nutritional quality of the school environment and student BMI. Thus, current federal standards regulating snacks in US schools (i.e., Smart Snacks) are an important element of a comprehensive strategy to improve the school nutrition environment and reduce rates of childhood obesity.

School Food and Beverage Availability and Children's Diet, Purchasing, and Obesity: Evidence From a Natural Experiment

PURPOSE

Existing evidence on relationships between school food environments and children's in-school purchases, dietary behaviors, and body composition is based on observational studies that are vulnerable to residential selection bias.

METHODS

This study leveraged exogenous variation in school environments generated by the natural experiment due to military parents' assignment to installations. We analyzed 1,010 child-wave observations from the Military Teenagers Environments, Exercise, and Nutrition Study collected during 2013-2015. Using multiple linear and logistic regression, we examined whether the number of competitive food and beverage (CF&B) items available for purchase in school, overall and by type (unhealthy, healthy, neutral), was associated with in-school food purchases, dietary behaviors, and body mass index (BMI) outcomes. Covariates included child and family characteristics and the healthiness of the home food environment.

RESULTS

Unhealthy item availability was positively associated with purchasing any sweets (adjusted odds ratio [AOR], 1.30; p < .01), snacks (AOR, 1.23; p < .01), and sugar-sweetened beverages (AOR, 1.19; p = .01). However, there were no significant associations with overall food and beverage intake (e.g., sweets, soda) nor BMI outcomes. The home food environment was significantly associated with all outcomes.

CONCLUSIONS

Access to unhealthy CF&B items may influence in-school purchases but does not appear to influence overall dietary behaviors and BMI outcomes. Substitution of caloric intake across locations within versus outside of school may play a role in explaining why purchases were associated with unhealthy CF&B availability but overall diet and downstream BMI were not.

The impact of state policies for school-based BMI/fitness assessments on children's BMI outcomes in rural versus urban schools: Evidence from a natural experiment

Childhood obesity remains a public health crisis because of its alarming prevalence and potential for costly long-term health consequences, especially among rural children. Schools are considered natural loci for policies to combat obesity because children spend most of their active hours and consume a substantial share of their calories, at school. Recent state policy efforts have involved measuring children's BMI and/or fitness to notify parents or inform surveillance efforts, but the empirical evidence to date is far from definitive. This study leverages plausibly exogenous assignment of military families as a natural experiment to assess the association of such polices with children's BMI and obesogenic behaviors. The sample is stratified by urbanicity because of the likely differences in obesity prevalence and in environments necessary to support healthy lifestyles. Data were collected in 2013-2014 and analyzed in 2018-9. The policies were associated with lower odds of overweight (OR: 0.422; CI: 0.251-0.708) and at-risk of overweight (OR: 0.360; CI: 0.161-0.801) among children in rural, but not urban, schools. The policies were also associated with greater activity levels and less frequent intake of unhealthy foods, particularly among children attending rural schools. Results were robust to stratification based on urbanicity of the installation versus school, omission of family covariates, and other sensitivity analyses. Falsification checks on children's height, parental BMI outcomes, home food environments and neighborhood environments indicate findings are not driven by selection. BMI assessment policies were associated with children's BMI outcomes and health behaviors in rural, but not urban schools.

Food Trying and Liking Related to Grade Level and Meal Participation

School-based child nutrition programs provide students with meals and snacks that align with guidelines for a healthy eating pattern. However, participation is not universal, and research on the determinants of food selection is needed to improve school nutrition practices and policies. The purpose of this study was to examine the relationships between grade level (i.e., grade school, middle school, or high school) as well as meal participation category (i.e., only breakfast, only lunch, or both) and food trying and liking in a large urban school district. Outcomes were measured using an online survey completed by students from 2nd through 12th grade (n = 21,540). Breakfast and lunch item liking scores were higher among the grade school and middle school students than among the high school students. Breakfast and lunch liking scores were also higher among those who participated in both breakfast and lunch as opposed to those who only participated in one meal. Food item liking scores were positively correlated with the percentage of students who had tried the particular foods (r = 0.52, p < 0.001), and the number of foods tried was dependent on both grade level and meal participation category (F(4, 21,531) = 10.994, p < 0.001). In this survey of students, both grade level and meal participation category were found to be related to the liking of foods, while foods that were tried more often tended to be liked more. Future studies should consider grade level and meal participation when exploring student preferences. School nutrition programs should also consider these factors when assessing satisfaction.

Using natural experiments to improve public health evidence: a review of context and utility for obesity prevention

Background

Natural experiments are increasingly valued as a way to assess the health impact of health and non-health interventions when planned controlled experimental research designs may be infeasible or inappropriate to implement. This study sought to investigate the value of natural experiments by exploring how they have been used in practice. The study focused on obesity prevention research as one complex programme area for applying natural experiment studies.

Methods

A literature search sought obesity prevention research from January 1997 to December 2017 and identified 46 population health studies that self-described as a natural experiment.

Results

The majority of studies identified were published in the last 5 years, illustrating a more recent adoption of such opportunities. The majority of studies were evaluations of the impact of policies (n = 19), such as assessing changes to food labelling, food advertising or taxation on diet and obesity outcomes, or were built environment interventions (n = 17), such as the impact of built infrastructure on physical activity or access to healthy food. Research designs included quasi-experimental, pre-experimental and non-experimental methods. Few studies applied rigorous research designs to establish stronger causal inference, such as multiple pre/post measures, time series designs or comparison of change against an unexposed group. In general, researchers employed techniques to enhance the study utility but often were limited in the use of more rigorous study designs by ethical considerations and/or the particular context of the intervention.

Conclusion

Greater recognition of the utility and versatility of natural experiments in generating evidence for complex health issues like obesity prevention is needed. This review suggests that natural experiments may be underutilised as an approach for providing evidence of the effects of interventions, particularly for evaluating health outcomes of interventions when unexpected opportunities to gather evidence arise.

Stronger State School Nutrition Laws Are Associated With Healthier Eating Behaviors and Optimal Weight Status in US Adolescents

PURPOSE

To investigate relationships of farm-to-school, school meal, and competitive food state laws with eating behaviors and weight status and to examine interaction between different types of state laws.

DESIGN

Observational cohort study.

SETTINGS

US adolescents.

PARTICIPANTS

The NEXT study is a nationally representative sample of adolescents assessed annually for 7 years. Data (N = 2751) from students attending public schools from the first (W1) and third (W3) assessment waves (2010 and 2012), occurring during grades 10 and 12, respectively, of the NEXT study were included.

MEASURES

Eating behaviors and weight status of adolescents were linked with Classification of Laws Associated with School Students scoring for state laws.

ANALYSIS

Regression analyses examined associations of laws with intake and weight status, accounting for complex survey design and school-level clustering.

RESULTS

Adolescents in states with strong farm-to-school laws had greater W1 whole fruit, lower soda, and snack intakes versus those in states with no laws. Strong school meal laws were associated with lower W1 soda intake. Adolescents in states with strong competitive food laws had lower soda intake and overweight/obesity odds than those in states with no laws in W3. Strong farm-to-school laws were inversely associated with W3 overweight/obesity odds only in states with strong competitive food laws.

CONCLUSIONS

Stronger laws governing school nutrition were related to healthier eating behaviors and optimal weight status in this nationally representative sample of adolescents. Further, farm-to-school laws may be more effective in reducing obesity when combined with strong competitive food legislation.

Characteristics of the school food environment associated with hypertension and obesity in Brazilian adolescents: a multilevel analysis of the Study of Cardiovascular Risks in Adolescents (ERICA)

Objective:

To characterize the food environment in schools that participated in the Study of Cardiovascular Risks in Adolescents (ERICA) and to identify individual and contextual factors associated with hypertension and obesity.

Design:

National school-based survey.

Setting:

Blood pressure, weight and height were measured, and characteristics of the schools were obtained in interviews with the principals. For each outcome, multilevel models of mixed effects were applied by logistic regression.

Participants:

School-going adolescents aged 12–17 years.

Results:

A total of 73 399 adolescents were evaluated. The prevalence of hypertension was 9·6 (95 % CI 9·0, 10·3) % and that of obesity was 8·4 (95 % CI 7·9, 8·9) %. Approximately 50 % of the adolescents were able to purchase food at school and in its immediate vicinity and 82 % had access to no-charge meals through Brazil’s National School Feeding Program. In the adjusted analysis, hypertension was associated (OR; 95 % CI) with the consumption of meals prepared on the school premises (0·79; 0·69, 0·92), the sale of food in the school’s immediate vicinity (0·67; 0·48, 0·95) and the purchase of food in the school cafeteria (1·29; 1·11, 1·49). It was observed that there were lower odds of obesity among students who were offered meals prepared on the school premises (0·68; 0·54, 0·87).

Conclusions:

High frequency of sales of ultra-processed foods in schools was identified. Contextual and individual characteristics in the school food environment were associated with hypertension and obesity, pointing to the need for regulation and supervision of these spaces.

Ultra-processed food consumption by Brazilian adolescents in cafeterias and school meals

This cross-sectional study utilized the National School Health Survey 2015 database to assess the association between school cafeterias; the meals offered by the Brazilian School Food Program (PNAE); and the consumption of industrialized/ultra-processed salty foods, sweets, and soft drinks among Brazilian adolescents. A sample of 102,072 adolescents, aged 11-19 years, who were enrolled in the 9th grade completed the survey. The evaluated outcome was the consumption of industrialized/ultra-processed salty foods, sweets, and soft drinks. A Poisson regression model-based multivariate analysis was performed. The effect measure was the prevalence ratio (PR) with its respective 95% confidence intervals (CIs). The results indicated that Brazilian adolescents who attended schools without meals offered through the PNAE had a higher probability of regularly (≥5 times/week) consuming ultra-processed salty foods [PR = 1.06, CI = 1.01-1.11] and soft drinks [PR = 1.08, CI = 1.03-1.14] compared to those who attended schools that offered PNAE meals. Moreover, the presence of a school cafeteria was associated with a higher probability to consume industrialized/ultra-processed salty foods [PR = 1.05, CI = 1.02-1.08], sweets [PR = 1.09, CI = 1.07-1.11], and soft drinks [PR = 1.10, CI = 1.07-1.13]. School meals appear to be associated with the consumption of ultra-processed foods by Brazilian adolescents, indicating areas for health promotion programs.

Hungry for more: key stakeholders' support for more stringent school food policies

OBJECTIVE

School food policies are an important component of comprehensive strategies to address child obesity and improve children's health. Evaluations have demonstrated that these policies can be initially well accepted and appropriately implemented, however little is known about how acceptance levels may change over time. The present study aimed to re-evaluate a school food policy 10 years after its introduction to assess key stakeholders' support for various policy extensions that would strengthen the scope of the policy.

DESIGN

Online surveys administered 1 year after policy introduction (n 607, 2008) and 10 years after policy introduction (n 307, 2016).

SETTING

Western Australia.ParticipantsSchool principals, teachers, canteen managers and presidents of parents &amp; citizens associations from Western Australian Government primary schools.

RESULTS

At both time points, and especially at time 2 (10 years post policy implementation), high levels of support were reported for the policy and possible policy extensions. Support was strongest for an additional requirement to integrate the canteen menu with the classroom health curriculum.

CONCLUSIONS

The results suggest that once a policy has become embedded into school practices, stakeholders may be receptive to modifications that strengthen the policy to enhance its potential effects on children's diets.

Systematic Review of Natural Experiments for Childhood Obesity Prevention and Control

CONTEXT

The National Academy of Medicine recommends childhood obesity prevention efforts making healthier options the passive choice. This review evaluated the effectiveness of population-level policies and programs from natural experiments for childhood obesity prevention.

EVIDENCE ACQUISTION

The search included PubMed, CINAHL, PsycINFO, and EconLit from 2000 to 2017 for policies evaluated by natural experiments reporting childhood BMI outcomes. The studies were analyzed in 2017-2018. Interventions were classified by environmental focus (food/beverage, physical activity, or both) and stratified by setting (school, community, both). Risk of bias was evaluated for each study.

EVIDENCE SYNTHESIS

Of 33 natural experiments, most (73%) took place in the school setting only. The most common environmental focus in any setting was food/beverage (48%). All four studies that focused on both food/beverage and physical activity in schools demonstrated decreased prevalence of overweight/obesity or BMI z-score by 0.04-0.17. BMI decreased in all four studies in both school and community settings. The largest effect size was a decrease in BMI z-score of 0.5, but most were <0.25. The risk of bias was high for most (76%) studies. Most (63%) of the eight studies with low/medium risk of bias took place in the school setting focused on the food/beverage environment; effects on BMI were mixed.

CONCLUSIONS

Natural experiments evaluating school-based policies focusing on both the food/beverage and physical activity environments (versus targeting only one) consistently showed improvement in BMI. However, most studies had high risk of bias, highlighting the need for improved methods for evaluation of natural experiments for childhood obesity prevention.

Leveraging the Public School System to Combat Adolescent Obesity: The Limits of Arkansas's Statewide Policy Initiative

PURPOSE

This study assessed the effectiveness of one of the earliest statewide policy initiatives to address obesity via schools-Arkansas's Act 1220 of 2003-on adolescent obesity. The Act required public schools in Arkansas to conduct body mass index (BMI) screening and reporting, restrict access to vending machines, and establish physical education and nutrition standards.

METHODS

To determine the effect of Act 1220 as a whole, this study analyzed data representative of adolescents in grades 9-12 from the Youth Risk Behavior Survey using the quasi-experimental method of difference-in-differences. Changes in adolescents' weight outcomes in Arkansas before (1999 and 2001) and after (2005, 2007, and 2009) the implementation of Act 1220 were compared to changes in weight outcomes for adolescents from the neighboring state of Missouri across the same time period.

RESULTS

Arkansas's Act 1220 did not significantly influence adolescents' BMI-for-age z-scores (-.017; 95% confidence interval [CI] [-.097, .063]; p = .68). Further, the Act did not lead to significant reductions in BMI-for-age z-scores among adolescents who were either overweight (-.003; 95% CI [-.043, .036]; p = .86) or obese (-.010; 95% CI [-.070, .051]; p = .75). Results remain robust to adjustments for self-report bias in height and weight as well as a set of alternative comparison states.

CONCLUSIONS

Preventing adolescent overweight and obesity is unlikely to occur through such large-scale policy initiatives alone.

Methods for Evaluating Natural Experiments in Obesity: A Systematic Review

BACKGROUND

Given the obesity pandemic, rigorous methodological approaches, including natural experiments, are needed.

PURPOSE

To identify studies that report effects of programs, policies, or built environment changes on obesity prevention and control and to describe their methods.

DATA SOURCES

PubMed, CINAHL, PsycINFO, and EconLit (January 2000 to August 2017).

STUDY SELECTION

Natural experiments and experimental studies evaluating a program, policy, or built environment change in U.S. or non-U.S. populations by using measures of obesity or obesity-related health behaviors.

DATA EXTRACTION

2 reviewers serially extracted data on study design, population characteristics, data sources and linkages, measures, and analytic methods and independently evaluated risk of bias.

DATA SYNTHESIS

294 studies (188 U.S., 106 non-U.S.) were identified, including 156 natural experiments (53%), 118 experimental studies (40%), and 20 (7%) with unclear study design. Studies used 106 (71 U.S., 35 non-U.S.) data systems; 37% of the U.S. data systems were linked to another data source. For outcomes, 112 studies reported childhood weight and 32 adult weight; 152 had physical activity and 148 had dietary measures. For analysis, natural experiments most commonly used cross-sectional comparisons of exposed and unexposed groups (n = 55 [35%]). Most natural experiments had a high risk of bias, and 63% had weak handling of withdrawals and dropouts.

LIMITATION

Outcomes restricted to obesity measures and health behaviors; inconsistent or unclear descriptions of natural experiment designs; and imperfect methods for assessing risk of bias in natural experiments.

CONCLUSION

Many methodologically diverse natural experiments and experimental studies were identified that reported effects of U.S. and non-U.S. programs, policies, or built environment changes on obesity prevention and control. The findings reinforce the need for methodological and analytic advances that would strengthen evaluations of obesity prevention and control initiatives.

PRIMARY FUNDING SOURCE

National Institutes of Health, Office of Disease Prevention, and Agency for Healthcare Research and Quality. (PROSPERO: CRD42017055750).

Stakeholder perceptions of a school food policy ten years on

Objective

To assess (i) the extent to which stakeholders have accepted and implemented a Healthy Food and Drink Policy for schools a decade after its introduction and (ii) any resulting implications for canteen profitability.

Design

Online survey distributed via electronic newsletter to school principals.

Setting

Western Australian public schools.

Subjects

Principals, teachers, canteen managers, and parents and citizens committee presidents (n307).

Results

Large majorities of respondents reported that the policy has made the foods and drinks provided in schools healthier (85 %) and that the policy constitutes a good opportunity to teach children about healthy eating (90 %). Only small proportions of respondents felt it had been difficult to implement the policy in their schools (13 %) or that the policy fails to accommodate parents’ rights to choose the foods consumed by their children (16 %). Most of the policy outcomes assessed in both the initial post-implementation evaluation (2008) and the 10-year follow-up evaluation (2016) demonstrated significant improvement over time.

Conclusions

The study results indicate that comprehensive school food policies can favourably influence the foods and drinks provided on school premises and can be highly acceptable to key stakeholders, without adversely affecting profitability. The results are encouraging for policy makers in other jurisdictions considering the implementation of similar policies.