Students for Nutrition and eXercise (SNaX)

Currently in the United States, over 13 million children and adolescents are obese. Many health-related conditions are linked to obesity, including heart disease, stroke, type 2 diabetes, and certain types of cancer. Among children, including those from low-income households, obesity can be prevented through healthy eating habits and physical activity. Schools have a unique opportunity to teach students about the importance of healthy behaviors. To improve overall student health, the Centers for Disease Control and Prevention (CDC) recommends that schools promote healthy dietary behaviors and physical activity through programs that include students and their families. In addition, CDC recommends that parents help children maintain a healthy weight by balancing the calories their child consumes from food and beverages with the calories their child uses through physical activity and normal growth. School-based interventions that encourage nutrition and physical activity among children, including those who come from low-income households, are vital to decrease rates of obesity and related health problems.

Students for Nutrition and eXercise (SNaX) is a school-wide obesity prevention program for middle school students that promotes healthy eating and physical activity. In the randomized controlled trial (RCT), SNaX was designed as a 5-week program. The program has been modified over time to include some additional activities. The program currently available for dissemination is designed to be completed over the course of a semester. The intervention is based on social cognitive theories. Because school policies require schools to provide healthy food, one goal of SNaX is to increase the number of students served lunch in the cafeteria, including students eligible for free and reduced-price meals. Other goals include increasing fruit, vegetable, and water consumption and decreasing school snack sales.

A designated wellness coordinator manages the implementation of the program and follows the steps outlined in the SNaX Manual. The RCT intervention content consisted of five week-long units:

-- Unit 1, Hydrate for Health, conveys the importance of water consumption and the benefits of water relative to sports drinks, energy drinks, and soda.
-- Unit 2, Know Your Options, describes the healthy foods offered in the school cafeteria.
-- Unit 3, The Power of Fruits and Veggies, promotes the consumption of fruits and vegetables at school and at home.
-- Unit 4, On the Move, focuses on the benefits of physical activity.
-- Unit 5, Lose the Tube, encourages students to reduce their screen time (time using a television, computer, tablet, phone, or gaming device).

The content of these units is delivered through various components of the intervention:

-- School-wide messaging. Marketing tools to promote the program include a 30-minute video played at a school-wide assembly, weekly messages delivered using the school’s public announcement (PA) system, nutrition and physical activity posters and banners displayed in the school, and access to the SNaX mobile device application.

-- Cafeteria food changes and promotion. The cafeteria encourages healthier food consumption by setting up and maintaining hydration stations, ensuring that a greater variety of healthier options (e.g., sliced or bite-sized fruits) are served in the cafeteria, coordinating taste tests, and coordinating the placement of SNaX nutrition posters in or near the cafeteria.

-- Classroom lessons and activities. In the RCT, five classroom lessons were delivered one per week by classroom teachers who received scripted lesson plans. Activities (e.g., game show, role plays) accompanied each lesson. The current manual includes lesson plans with these same core activities, as well as additional activities, and is designed to be implemented over the course of a semester.

-- Parent involvement. Parents complete SNaX parent activities with their child to learn more about healthy eating and physical activity. They are also encouraged to volunteer with lunchtime activities (e.g., taste tests) in the school.

-- Student involvement. Students are trained as peer leaders to encourage and model healthy behaviors and engage other students. They learn how to discuss SNaX messages with peers and family and then lead lunchtime sessions that involve discussing SNaX messages; conducting taste tests with samples from the cafeteria (i.e., water, fruit, vegetables); and distributing buttons, wristbands, and bookmarks.

-- Time to establish a SNaX leadership team, review the SNaX manual and materials, and train student advocates (the amount of time needed varies based on school resources)
-- 15–30 minutes for each SNaX activity (e.g., unit lessons, lunchtime activities, trivia games, role playing)

The original intervention targeted middle school students in schools in lower-income communities, but the intervention is applicable for all students in middle schools.

This intervention is intended to be implemented in school and home settings.

Required resources to implement the program include the following:
-- SNaX website for students and parents
-- SNaX website for teachers

Costs associated with the program’s implementation are not provided.

A randomized controlled trial conducted in Los Angeles, California, compared outcomes in five middle schools receiving SNaX with those of five middle schools in a wait-list control group. Eligible schools had a student body with at least half of students eligible for the National School Lunch Program (NSLP), to ensure a high proportion of low-income students, and less than 900 seventh graders. Randomization occurred at the school level. Over a 4-year period, the intervention was implemented school wide in each intervention school for one spring semester.

In all intervention schools, only seventh-grade students received the peer leader education and served as peer leaders. Seventh graders were also given consent forms to participate in surveys and other student-level data collection. Of the 4,022 eligible seventh-grade students, 3,211 completed baseline surveys.

Across the sample (all students in all participating schools), 74.7% of students were Latino, 14.2% were African American, 5.7% were White, and 5.5% were Asian/Pacific Islander. The majority (84%) qualified for the NSLP’s free and reduced-price meals, and 19.8% were physically fit based on a physical fitness test that was administered by the school. The average number of seventh graders in each school was 484. At baseline, the groups did not differ on variables of age, gender, race/ethnicity, body mass index, NSLP eligibility, attitudes about eating cafeteria food, attitudes about drinking water, intentions to drink tap water, and water consumption. However, the groups did differ on baseline knowledge of healthy eating and physical activity, intentions to drink water from a refillable bottle, and likelihood of being born in the United States.

The main outcome measures were fruit portions served by the cafeteria, lunches served by the cafeteria, and snacks sales. These outcomes were assessed schoolwide at three time points (before, during, and after the intervention) through cafeteria and school store data. For each day of the intervention semester, the schools provided cafeteria records (number of students obtaining lunch by NSLP eligibility and number of fruit and vegetable servings) using point-of-sale data collected electronically, as well as school store data (number of snacks, such as cookies, sold) tracked using paper or spreadsheet files. The total number of students present each day was used to calculate a proportion that represented the fruit servings, vegetable servings, and meals served, as well as the number of snacks sold, per student per day, which was averaged for the days before, during, and after the intervention. The number of cafeteria lunches served was analyzed for all students and for students who were eligible and not eligible for NSLP.

Secondary outcomes were attitudes about eating cafeteria food, attitudes about drinking water, knowledge about healthy eating and physical activity, intentions to drink tap water, intentions to drink water from a refillable water bottle, tap water consumption, and water consumption using a refillable bottle. These outcomes were assessed among seventh graders using a survey at baseline and after the intervention. Most survey items used Likert scales. For example, one question asked, “On a scale from 0 to 10, how do you feel about drinking water?” with response options ranging from 0 (“very negatively”) to 10 (“very positively”). Water consumption was measured by asking, “How often do you usually drink tap water/use a refillable water bottle to drink water?” with the response options being “every day,” “a few times a week,” “once a week,” “twice a month,” “once a month,” “less than once a month,” or “never.”

• From before the intervention to during the intervention, intervention group schools had a greater increase in fruit servings compared with control group schools (p<.01). The group difference in fruit servings was not significant from before to after the intervention.

• From before the intervention to during the intervention, the number of cafeteria lunches served decreased in control group schools but remained the same in intervention group schools (p<.001). From before the intervention to after the intervention, the number of lunches served decreased more in control group schools than in intervention group schools (p<.01).

• Compared with control group schools, intervention group schools had a greater decrease in snack sales from before the intervention to during the intervention (p<.001) and from before the intervention to after the intervention (p<.01).

Additional Findings

• From before to after the intervention, compared with control group students, intervention group students had greater improvement in knowledge about healthy eating and physical activity (p<.01) and intentions to drink from a refillable bottle (p<.05), as well as improvement in attitudes about eating cafeteria food (p<.05), intentions to drink tap water (p<.05), and tap water consumption (p<.05). Attitudes about drinking water worsened more among control group students than among intervention group students (p<.05).
• Among students receiving a free or reduced-price lunch, the number of lunches served increased in intervention group schools and decreased in control group schools from before to during the intervention (p<.01) and from before to after the intervention (p<.01). Among students paying full price for lunch, the number of lunches served remained the same in intervention group schools and decreased in control group schools from before to during the intervention (p<.001) and from before to after the intervention (p<.001).