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Planet Health

Blueprints Program Rating: Promising

A two-year school-based health behavior intervention designed to reduce obesity among students in grades 6-8 by increasing energy expenditure while promoting key dietary behaviors. The program has only shown impacts on obesity outcomes for girls.

  • Steven Gortmaker
  • Planet Health
  • Harvard School of Public Health
  • Prevention Research Center on Nutrition and Physical Activity
  • 677 Huntington Ave. 7th Floor
  • Boston, MA 02115
  • www.hsph.harvard.edu/prc/projects/planet
  • Obesity

    Program Type

    • School - Individual Strategies

    Program Setting

    • School

    Continuum of Intervention

    • Universal Prevention (Entire Population)

    A two-year school-based health behavior intervention designed to reduce obesity among students in grades 6-8 by increasing energy expenditure while promoting key dietary behaviors. The program has only shown impacts on obesity outcomes for girls.

      Age

      • Early Adolescence (12-14) - Middle School

      Gender

      • Male and Female

      Gender Specific Findings

      • Female

      Race/Ethnicity

      • All Race/Ethnicity

      Race/Ethnicity Specific Findings

      • African American

      Race/Ethnicity/Gender Details

      The program influenced obesity outcomes for girls but not for boys. There is some evidence that the program works better for African American girls than white or Hispanic girls.

      Moderate and vigorous physical activity, television viewing, fruit and vegeable intake.

      • Individual
      Protective Factors
      • Individual: Exercise

      The Planet Health program is a two-year intervention designed to reduce obesity by increasing energy expenditure while promoting key dietary behaviors. The curriculum introduces and reinforces five simple health messages or goals: 1) Be physically active every day; 2) Limit your screen time to no more than two hours per day; 3) Eat five or more servings of fruits and vegetables (combined) daily; 4) Eat more whole grains and less added sugar; and 5) Eat foods low in saturated fat and containing no trans fat. The Planet Health curriculum includes teacher training workshops, classroom lessons, PE materials and wellness sessions. Classroom components are designed to fit into 45-minute periods and are designed to be inter-disciplinary. Each program theme is addressed in one lesson per subject (language arts, math, science and social studies) for a total of 16 core lessons each in year 1 and year 2, for a total of 32 lessons.

      The Planet Health program is a two-year intervention designed to reduce obesity by increasing energy expenditure while promoting key dietary behaviors. The curriculum introduces and reinforces five simple health messages or goals: 1) Be physically active every day; 2) Limit your screen time to no more than two hours per day; 3) Eat five or more servings of fruits and vegetables (combined) daily; 4) Eat more whole grains and less added sugar; and 5) Eat foods low in saturated fat and containing no trans fat.

      The Planet Health curriculum includes teacher training workshops, classroom lessons, PE materials and wellness sessions. Classroom components are designed to fit into 45-minute periods and are designed to be inter-disciplinary, with program themes taught in language arts, math, science, and social studies. Each theme is taught in one lesson per subject, for a total of 16 core lessons each per year (32 total lessons over two years). Lessons consist of behavioral and learning objectives, homework activities, student resources and handouts. In addition to the classroom components, there is a 2-week awareness campaign designed to reduce television viewing.

      Classroom teachers receive 3 hours of in-person training, while physical education teachers receive 5 hours of training. The training consists of an interactive PowerPoint presentation that models the methods of the program, engages the learners' current knowledge, promotes reflection and discussion, and encourages learners to compare their current knowledge and behaviors with those suggested by the book and to create plans and goals for the future.

      The Planet Health intervention focuses on improving the activity and dietary behaviors of all students, therefore reducing the stigma associated with singling out youth who are already obese. This population-based approach aims to both reduce obesity among those who are already obese and prevent new cases.

      The Planet Health intervention is based on concepts from behavioral-choice and social-cognitive theories of individual change. Behavioral-choice components of the intervention encourage participants to "make space" for more activity in their lives by reducing television time. The Planet Health intervention uses social-cognitive theory to illustrate the importance of social and environmental factors that influence both psychosocial and behavioral risk factors for obesity.

      • Behavioral

      Evaluation of the Planet Health intervention involved a randomized, controlled trial with 5 intervention and 5 control schools. The sample included 1,295 students from public schools in four urban Boston (MA) communities. Planet Health sessions were delivered within existing curricula using classroom teachers. Lessons focused on decreasing television viewing and consumption of high-fat foods, while increasing fruit/vegetable intake and physical activity. Data were collected over two years: baseline data was collected on a cohort of students at the beginning of grades 6 and 7 in fall 1995, with post-test data collected in spring 1997 (grades 7 and 8).

      Gortmaker et al. (1999)
      Planet Health intervention had some success in reducing obesity among girls, but no significant differences were observed among boys. Reductions were found in self-reported television viewing among both boys and girls, and girls in the intervention schools experienced increases in fruit and vegetable consumption and a reduction in overall dietary intake.

      Austin et al. (2005)
      The Planet Health intervention resulted in a reduced risk of using self-induced vomiting/laxatives or diet pills to control weight in the past 30 days, among a subgroup of adolescent girls.

      Gortmaker et al. (1999)

      • The Planet Health intervention significantly reduced obesity among girls in the intervention schools, when compared to the control conditions.
      • The Planet Health intervention did not significantly reduce obesity among boys.
      • Planet Health girls reduced dietary intake, increased fruit and vegetable consumption and viewed less television than control girls.

      Austin et al. (2005)

      • Girls in Planet Health intervention schools were less than half as likely to report purging or using diet pills at post-test compared with girls in control schools.

      Several secondary outcomes that were thought to be correlated with obesity were included in the analysis. Among girls, only television viewing was found to significantly predict obesity (OR = 0.85, p = .02) and mediate the intervention effect.

      Gortmaker et al. (1999)
      Effect sizes were small to medium for the two significant outcomes. Adjusted odds ratios were .47 for obesity prevention and 2.16 for obesity remission.

      Austin et al. (2005)
      Effect sizes were generally medium for the full sample of 480 girls, and large for girls who reported being non-dieters at baseline. Additionally, researchers estimate that 59% of disordered weight-control behavior among girls in control schools might have been prevented had they received the Planet Health intervention.

      Research evidence shows that the program only works for girls. There were no results for boys. Specifically, the program works better for African American girls than for White or Hispanic girls.

      Gortmaker et al. (1999); Austin et al. (2005)

      • The evaluation suffered from low participation rates. Only 65% of eligible students participated.
      • Dietary intake and physical activity measures were based on self-report, and potentially biased.
      • Some differences by race showed between the conditions at baseline.

      In 2003, CDC researchers conducted an independent economic analysis of Planet Health based on estimated program costs of $14 per student per year (this cost estimate included teachers being paid for their training time). For every dollar spent on middle school Planet Health programs, researchers projected a savings of $1.20 in medical costs and lost wages by the time students reach middle age (40 to 65 years of age) (Wang et. al. 2003).

      • Blueprints: Promising

      Austin, S., Field, A., Wiecha, J., Peterson, K., & Gortmaker, S. (2005). The impact of a school-based obesity prevention trial on disordered weight-control behaviors in early adolescent girls. Archives of Pediatric Adolescent Medicine, 159, 225-230.

      Gortmaker, S. Peterson, K., Wiecha, J., Sobol, A., Dixit, S., Fox, M., & Laird, N. (1999). Reducing obesity via a school-based interdisciplinary intervention among youth. Archives of Pediatric Adolescent Medicine, 153, 409-418.

      Steven Gortmaker
      Harvard Center for Children's Health
      Harvard School of Public Health
      677 Huntington Ave. 7th Floor
      Boston, MA 02115
      Website: www.hsph.harvard.edu.prc/projects/planet
      Email: sgortmak@hsph.harvard.edu
      Harvard Prevention Research Ctr: (617) 384-8919
      Email: hprc@hsph.harvard.edu

      Study 1

      Gortmaker, S. Peterson, K., Wiecha, J., Sobol, A., Dixit, S., Fox, M., & Laird, N. (1999). Reducing obesity via a school-based interdisciplinary intervention among youth. Archives of Pediatric Adolescent Medicine, 153, 409-418.

      Study 2

      Austin, S., Field, A., Wiecha, J., Peterson, K., & Gortmaker, S. (2005). The impact of a school-based obesity prevention trial on disordered weight-control behaviors in early adolescent girls. Archives of Pediatric Adolescent Medicine, 159, 225-230.

      Gortmaker, S. Peterson, K., Wiecha, J., Sobol, A., Dixit, S., Fox, M. and Laird, N. (1999). Reducing obesity via a school-based interdisciplinary intervention among youth. Archives of Pediatric Adolescent Medicine, 153, 409-418.

      Evaluation Methodology

      Design: Evaluation of the Planet Health intervention involved a randomized, controlled trial with 5 intervention and 5 control schools. Data were collected over two years: baseline data were collected on a cohort of students at the beginning of grades 6 and 7 in fall 1995, with post-test data collected in spring 1997 (grades 7 and 8). The sample included 1,295 students from public schools in four urban Boston (MA) communities. Post-test data were collected in spring 1997 on 83% of the baseline sample. Planet Health sessions were delivered within existing curricula using classroom teachers. Lessons focused on decreasing television viewing and consumption of high-fat foods, while increasing fruit/vegetable intake and physical activity.

      Schools were the unit of randomization. Recruitment of schools was based on willingness to implement the classroom and physical education curriculum. Control schools received their usual health curricula and PE classes.

      Recruitment: Baseline data were collected in fall 1995 on 1,560 students in both intervention and control schools. Overall participation rate was 64.5% in control schools and 64.8% in intervention schools. A total of five schools required active parental consent. Consent rates were 58% among schools with active consent and 89% among schools with passive consent. The analysis was based on 1,295 students who completed both baseline and post-test data.

      Attrition: Post-test data were collected in spring 1997 on 83% of the baseline sample (n = 1,295). Students were excluded who transferred schools, were in special education classes or were in the wrong grade. It should be noted that students who completed the Spanish-language version of the questionnaire (5% of eligible students) were excluded from the analysis.

      Sample: The sample used for analysis consisted of 1,295 students who completed both baseline and post-test assessments. Of these students, 48% were female and 52% male. Average student age was approximately 12 years old. Racial/ethnic breakdown was as follows: 66% white, 13% African American, 13% Hispanic, 8% Asian/Pacific Islander, 2% American Indian and 7% other.

      Measures: The primary outcome measures were obesity prevalence, incidence and obesity remission (a reduction in obesity among those already obese). Obesity was defined using a composite indicator based on a body-mass index and a triceps skinfold value greater than (or equal to) age- and sex-specific 85th percentile. Researchers measured change in obesity from baseline (fall 1995) to post-test (spring 1997).

      Secondary outcomes: Measures of television viewing, physical activity and dietary intake, as well as other sociodemographic and behavioral variables were obtained from a Food and Activity Survey completed by youth. The survey included an 11-item 'Television and Video' measure (estimate of total television viewing), a 16-item 'Youth Activity Questionnaire' (an estimate of time spent in moderate and vigorous physical activity) and the 'Youth Food Frequency Questionnaire' (assessment of intake of fruits, vegetables and fat).

      Analysis: Because schools were randomized, rather than students, a generalized estimated equation method was used to adjust for the individual-level covariates under cluster randomization, with schools nested within experimental conditions. Separate regression estimates were estimated for boys and girls. Analyses were conducted using an intent-to-treat protocol, with participants analyzed in their original randomized condition irrespective of the number of Planet Health sessions attended. To control for missing behavioral data, indicator variables with mean substitution were used. Researchers claim the mean substitution variables did not appear to affect the results of the analysis, but the technique is generally not appropriate.

      Outcomes

      The prevalence of obesity among girls in the Planet Health intervention schools was significantly reduced, when compared to girls in the control condition. There were no significant differences in obesity measures among boys.

      Implementation fidelity: Implementation analysis revealed 87% of classroom teachers and 100% of PE teachers completed the training sessions. Classroom teachers reported they completed an average of 3.5 lessons per year (out of a minimum of 4 per subject). PE teachers reported they completed an average of 8.2 micro-units per year (out of 30).

      Baseline equivalence: Prior to randomization, schools were matched and balanced for factors that could affect study outcomes. These included school size, ethnic composition, school food services and physical education curricula. There was a slight difference in median household income between the zip codes associated with intervention and control schools, with intervention schools averaging $36,020 and control schools averaging $34,200.

      Baseline data stratified by sex revealed no significant differences among the 1,560 intervention and control students in mean values of age, body-mass index, triceps skinfold or obesity. There were some differences in ethnic composition: higher percentages of African American girls (17% vs 10%) and Hispanic boys (18% vs 12%) were in control schools.

      Differential attrition: Post-test data were collected in spring 1997 on 83% of the baseline sample. For girls, data were collected for 82% of control and 81% of intervention students. For boys, data were collected for 86% of control and 83% of intervention students. Among girls, there were no significant baseline differences in rates of follow-up at baseline. For boys who were obese, a lower rate of follow-up was observed in the intervention condition (87% in the intervention vs 94% in the control condition).

      Examining completers only, the intervention and control group had similar baseline sociodemographic, anthropometric, diet and physical activity data. Among girls, there was a difference in the prevalence of African American students (16% control vs 10% intervention), which is about the same distribution as at baseline.

      Posttest

      Obesity: There were significant results in 2 of 3 obesity measures for girls. When compared to girls in the control condition, girls in the Planet Health schools had significantly reduced obesity prevalence and significantly greater obesity remission. None of the three obesity outcomes for boys were significant.

      There was some evidence that the program worked better for African-American girls than white or Hispanic girls.

      Secondary outcomes: Among girls, 3 of 5 secondary outcome measures achieved significance. Girls in the intervention schools reported reduced dietary intake, increased fruit and vegetable consumption and less television viewing, when compared to girls in the control condition. Among boys, 1 of 5 secondary outcome measures achieved significance. Boys in the intervention schools reported less television viewing when compared to boys in the control condition.

      Austin, S., Field, A., Wiecha, J., Peterson, K. and Gortmaker, S. (2005). The impact of a school-based obesity prevention trial on disordered weight-control behaviors in early adolescent girls. Archives of Pediatric Adolescent Medicine, 159, 225-230.

      This study examined the effects of Planet Health on the use of disordered weight control strategies such as vomiting, laxatives and diet pills by middle school girls. The study used data from the sample described in Gortmaker et al. (1999).

      Evaluation Methodology

      Design: This evaluation assessed the impact of the Planet Health intervention on use of self-induced vomiting and laxative use (purging) and diet pills to control weight in adolescent girls. The study used 480 girls in the intervention and control schools who reported no use of diet pills or purging at baseline. It excluded 21 girls who reported these activities at baseline. It then examined the effects of the intervention on the risk of reporting a new case of purging or diet pill use to control weight at post-test (21 months later).

      Sample: The sample included a subgroup of 480 girls, age 10-14 (mean = 11.5 years). This subgroup was taken from a larger sample described in Gortmaker et al. (1999).

      Measures: Survey items on dieting, vomiting or taking laxatives (purging), and taking diet pills in the last 30 days to control weight were combined to create a single disordered weight-control variable for analysis. The composite variable was composed of the following survey questions:

      • During the past 30 days, did you diet to lose weight or to keep from gaining weight?
      • During the past 30 days, did you vomit or take laxatives to lose weight or to keep from gaining weight?
      • During the past 30 days, did you take diet pills to lose weight or to keep from gaining weight?

      Analysis: Data from 480 girls were used to examine the effects of the Planet Health intervention on the risk of reporting a new case of purging or diet pill use to control weight at post-test (21 months later). A generalized estimating equation (GEE) was used to account for design effects due to clustered sampling by school. The authors estimated the odds of reporting disordered weight-control behavior in the past 30 days at post-test among girls who did not report use of purging or diet pills at baseline. Baseline dieting, age, obesity and ethnicity were used as covariates in multivariate models. Girls who reported purging or using diet pills at baseline were excluded from the analysis.

      Outcomes

      Baseline equivalence: Compared with girls in the intervention schools, a greater proportion of girls in the control schools were African American (9.1% vs 15.9%) at baseline. Therefore, ethnicity was included in all multivariate models. Control and intervention participants did not differ significantly in the distribution of age or prevalence of overweight or dieting in the past month.

      Differential attrition: The cases used were subject to the same differential attrition as in Gortmaker et al. (1999).

      Posttest: Girls in intervention schools were less than half as likely to report purging or using diet pills at post-test compared to girls in control schools (OR = 0.41).

      Results appeared particularly strong among those who were non-dieters at baseline: among baseline non-dieters, girls in intervention schools were 12 times less likely than girls in control schools to report the use of purging or diet pills to control their weight at post-test.

      Long-term: No follow-up data were gathered.