Cost-free and sustainable incentive increases healthy eating decisions during elementary school lunch

Abstract

We aimed to develop a cost-free and sustainable program to influence healthier eating decisions during elementary school lunch. Baseline food and beverage choices were assessed for 9 days during lunch service at two racially and economically diverse elementary schools in Spartanburg County, SC, USA. After being informed that the labeled items on the daily lunch menu represented the healthiest choice, students were allowed to ring a call bell in the cafeteria for public recognition when they chose all of the identified healthiest food and beverage items during lunch service. Using menus matched to the baseline phase, food and beverage choices were measured during a 9-day intervention phase. After 30 days, food and beverage choices were reassessed during a 3-day follow-up phase. Healthiest food & beverage choices increased 49% with >60% of students choosing non-flavored milk over flavored milk during the intervention phase. There was no difference in the success of the program between the two schools. The program continued and healthy eating decisions were significantly sustained at a 30-day follow-up assessment. Public recognition through bell ringing appears to be an effective practice to sustain increases in healthy eating decisions during elementary school lunch and warrants expansion to larger scale, longitudinal trials.

Introduction

Greater than 10% of the world's school age children are either overweight or obese.1 The US has one of the highest rates with 35.5% of elementary students (6–11 years old) either overweight or obese.2 The state of South Carolina and Spartanburg County, SC, mirror the US with 33.7% and 34.4%, respectively, of children either overweight or obese.3 From global to local communities, the prevalence of overweight and obese children is consistent and staggering. These children are at risk for numerous health problems, negative psychosocial consequences and lower school performance4, 5 with 70% of obese children become obese adults.6

Early intervention strategies are necessary to prevent poor developmental outcomes. A recent meta-analysis touted the effectiveness of school-based interventions (SBIs) to reduce childhood overweight and obesity;7 however, as highlighted by the editorial of Durant et al.,8 SBIs have tended to be large, expensive projects with a heterogeneity of approaches contributing to varied efficacies and the inability to be reliably reproduced. In agreement with the conclusion of Durant et al.8 that novel approaches and smaller efficacy studies are necessary before large scale implementation, we report here a cost-free and sustainable SBI model that can be universally implemented with minimal environmental changes yet considerable effectiveness.

Although healthier guidelines for the National School Lunch Program regulated by the United States Department of Agriculture are currently being considered,9 our SBI emphasizing healthiest lunch selections will remain relevant as special interest groups such as the International Dairy Foods Association (IDFA) and the National Milk Producers Federation (NMPF) are ensuring future guidelines require a variety of milk, including higher calorie, flavored milk, as lunch beverages.10 The argument from the IDFA and NMPF to include flavored milk is in part based on reported decreased milk consumption following the removal of flavored milk from schools.11 Here we report a SBI that effectively shifts the behavioral choice to non-flavored milk (100 calories, 1% fat) without removing flavored milk (140–170 calories, 0–1% fat) and with no decrease in total milk consumption. Furthermore, along with 99% of food providers offering more than one milk option, 71% offer more than one entrée option with varied fat and caloric values.12 Thus, even with improved United States Department of Agriculture regulation of nutrition, the majority of students will continue to have choices of foods with varied nutritional quality during their elementary school lunch.

Our within-subjects design measured students’ selections of food and milk during lunch to assess the effectiveness of an intervention of public recognition for choosing the identified healthiest food from the menu. Theoretically, intrinsic incentives and motivation are associated with more permanent behavioral changes compared with external rewards that effectively change behavior only as long as the reward is maintained.13 Our intention was to create an intrinsic reinforcement of pride and self-esteem through sustainable, extrinsic public recognition when students were allowed to ring a call bell in the cafeteria in front of their peers after choosing the identified healthiest lunch items with non-flavored milk.

Materials and methods

Subjects were kindergarten through sixth grade students from a suburban school with demographics similar to the adult population of its resident county (school 1 n=301±8.6; 45% female, 55% male; 63% Caucasian, 27% African–American, 4% Hispanic, 6% other; 41% free or reduced school lunch) and an urban school with a predominantly minority student population (school 2 n=264±6.8; 47% female, 53% male; 2% Caucasian, 95% African–American, 2% Hispanic, 2% other; 96% free or reduced school lunch). Students receiving lunch must choose one of three entrées, three side items and milk. At both schools, there were three milk options: non-flavored white (100 cal, 11 g sugar), chocolate (140 cal, 26 g sugar) and strawberry (170 cal, 30 g sugar) with a fourth choice of vanilla flavored milk (150 cal, 24 g sugar) available only at school 1. Healthiest menu items were identified daily by the food service provider on posted menus and with stickers in the service line during both baseline and intervention phases.

Data collection and intervention

Baseline and intervention phases consisted of 9 consecutive days during which the entrée, side items and milk type selected by each student along with the number of students selecting the complete healthy items menu plus non-flavored milk were recorded. After the baseline data collection, a single 4 min education session14 explained the food pyramid guide and informed the students that the daily identified menu items represented the healthiest lunch choice to receive proper nutrients across the food pyramid categories. Excess sugar consumed in 1 school year (180 days) if students drank chocolate (5.9 lbs), strawberry (7.5 lbs) or vanilla (5.5 lbs) milk instead of non-flavored, white milk were displayed in jars that remained in the cafeteria during the intervention phase. Students were informed that when they chose all of the healthiest menu items plus white milk, they would be allowed to ring a call bell in the cafeteria as public recognition of their healthy eating decision. After the intervention phase data collection, school administrators agreed to continue allowing students making the healthiest eating decisions to ring the bell in the cafeteria. After 30 days, a 3-day follow-up reassessed student's food item and beverage selections at school 1. The number of menu items selected was converted to percentages for each grade to allow equal weight in the overall analysis. Analysis of variance tests were used to identify significant (P<0.05) main effects and interactions between the experimental conditions (baseline or intervention), grades (K-6) and schools (1 or 2) with Bonferroni post hoc analysis.

Results

Lunch program participation did not differ between baseline (293±6.6; 266±8.2) and intervention (310±10.5; 261±5.5) phases for schools 1 and 2. Selection of the complete healthiest menu plus non-flavored milk increased for all grades at both schools during the intervention phase (F1,16=276.99, P<0.001; Figure 1). There was no interaction between phase and school indicating similar increases in healthy eating decisions (45.4±4.1%; 53.5±4.1%). There was a significant three-way interaction between phase, grade and school (F6,96=8.74, P<0.001) indicating differential increases in healthy eating decisions across the grades at each school; however, healthy eating decisions significantly increased for every grade at both schools. Increases in healthy eating decisions were significantly sustained at the 30-day follow-up (F2,4=51.39, P<0.001) with 20.0±5.3% of students continuing to choose the healthiest menu compared with 2.7±1.5% of students during three baseline days with matched menus.

Figure 1
figure1

Increases in the percent of students selecting the complete healthy menu with white milk from baseline phase to the intervention phase across grades for school 1 (a) and school 2 (b). Error bars represent s.e.

The intervention produced a greater influence on the selection of milk by students at both schools (Figure 2). At school 1 (Figures 2a and b), there was no effect on the total amount of milk consumed but there was a significant interaction between phase and type of milk selected (F3,24=193.65, P<0.001). During the intervention phase, there was a dramatic increase of 67% of students selecting white milk (t(8)=20.092, P=0.000) coupled with reductions in chocolate (t8=11.28, P<0.001) and vanilla (t8=8.6, P<0.001) milk selections. Similar effects were observed at school 2 (Figures 2c and d), with no effect on the total amount of milk consumed and a significant interaction (F3,24=440.16, P<0.001) between phase and milk choice with 72% of students selecting white milk (t8=17.94, P<0.001) and reductions in both chocolate (t(8)=24.404, P=0.000) and strawberry (t8=16.18, P<0.001) milk selections. The shift from the flavored milk (40–70% more calories) to non-flavored milk was sustained at the 30-day follow-up (F3,6=25.92, P<0.001) with 51.9±2.5% of students continuing to select white milk (t2=22.24, P<0.01) and sustained reductions in chocolate milk (38.4±1.4%; t2=5.97, P<0.05) as compared with the baseline phase.

Figure 2
figure2

Changes in milk type selection from baseline phase (a) to intervention phase (b) in school 1 and baseline phase (c) to intervention phase (d) for school 2. The other category in the bottom panels includes drink selections other than milk or water such as juice and soft drink beverages.

Discussion

This research identifies a cost-free and sustainable practice to increase healthy eating decisions during elementary school lunch service without substantial changes to the routine or environment. The keys to successful implementation are identifying the daily healthy food items and consistent recognition of students making the healthy eating decisions plus white milk through allowing those students to ring a call bell in public recognition of their healthy decision. It is worth noting the voluntary nature of students to both make a healthy eating decision and choose to ring the bell. There is no punishment or negative reinforcement and any student not wishing to receive public attention was not required to ring the bell. Our hope is the intrinsic, positive emotion associated with the brief public attention from the extrinsic action of ringing the bell will reinforce intrinsic pride and a sense of accomplishment for having made a healthy eating decision. In turn, this reinforcement might carry-over to sustainable changes in their future eating behavior.

The goal of this small efficacy study was to apply current motivational learning theory13 as a basis to create an evidenced-based, cost-free and sustainable model of cafeteria environments that place a high value on healthy eating decisions in order to influence healthier eating habits outside of the school cafeteria and ultimately reduce the prevalence of childhood overweight and obesity. Recognizing the limitations of short-term intervention data collection and the inability to monitor actual consumption of chosen foods, we are currently engaged in a longitudinal study across 14 elementary schools to track the long-term effectiveness of the program with relation to lunch food consumption and the ability to reduce the prevalence of overweight and obesity by comparing body mass index scores of students in participating and non-participating schools.

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Acknowledgements

We thank Susan Thomas, Emily Sheenan, Erica Samples, Covington Avent, Dominique Cox, Taylor Fenig, Bianca Harmon and Gwendolyn McDaniel for their assistance in data collection. We thank Peggy Luther and Ron Jones at Chartwells and the teachers, staff, principals and superintendent of the elementary schools for their cooperation and partnership. This study was approved by the Institutional Review Boards of Wofford College and the University of South Carolina-Upstate and supported by the Spartanburg Community Indicators Project, Spartanburg Regional Healthcare System Foundation and Wofford College. Supplementary information and instructions on how to implement this program in an elementary school along with a free multimedia tool kit are available at www.HealthyEatingDecisions.com.

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Correspondence to D W Pittman.

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Pittman, D., Parker, J., Getz, B. et al. Cost-free and sustainable incentive increases healthy eating decisions during elementary school lunch. Int J Obes 36, 76–79 (2012). https://doi.org/10.1038/ijo.2011.205

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Keywords

  • school-based intervention
  • positive reinforcement
  • childhood obesity

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