Table 1:

Description of Quantitative Measures Used to Assess Youth-leaders Pre- and Post-Intervention

Domain	Description
Demographics	Demographic measures included self-reported age, gender, race/ethnicity, and education level.
Weight Status	Height and weight were measured in duplicate and averaged. In cases where participants refused measurement, self-reported height and weight measures were accepted (8% of measures). Participants were then classified by weight status (normal, overweight/obese) using age-appropriate methods (BMI equation and standard cutoffs for participants >20 years old, and CDC BMI-for-Age percentile and standard cutoffs for participants <20 years old.)
Dietary Intake48
Total Calories, Calories from Sweetened Beverages, Fruit Servings, Vegetable Servings, Total Fat (grams)	Four measures of dietary intake were assessed: total calories, calories from sweetened beverages, fruit servings, and vegetable servings. These were estimated using the Block 2004 Food Frequency Questionnaire for Kids, which is a 77-item validated semi-quantitative FFQ that assesses the past 7-day intake.
Food-related Behavior31,47
Total Sugar-Sweetened Beverage (SSB) Purchasing (frequency), Total non-SSB Purchasing (frequency) Total FV purchasing (frequency) Healthy Food Purchasing Score Unhealthy Food Purchasing Score Healthy cooking preparation Score	Frequency of Food Purchasing: food acquired in the previous 7 days from a pre-defined list of 38 healthier (Cronbach’s alpha=0.88) and 28 less healthful foods and beverages (Cronbach’s alpha=0.79). SSB included regular soda, fruit drink, sports drink, energy drink, and sweetened tea. Non-SSB included water, diet soda, low-sugar flavored water, unsweetened tea, 100% fruit juice, and water drink mix. Healthy Cooking Preparation Score: reflects preparation methods used in the previous 7 days. Each food preparation method was assigned the following score based on the healthiness of the method: fried=−1, baked=+1, microwaved=+1, raw=+1, other=0. The total score for each cooking method was averaged and calculated taking into account the number of times food was prepared. The youth food preparation score ranged from −1 to +1, mean=0.46 (SD=0.71).
Psychosocial Factors31,46
Self-efficacy	A 13-item scale asking participants to rate how confident in they are in performing selected nutrition-related behaviors (example statement: I can eat a healthy breakfast even when I am running late for school or work). Participants could respond on a 4-point scale that included: I know I can (3), I think I can (2), I’m not sure I can (1), and I know I can’t (0). Responses were summed to create the scale score (possible range 0–39, Cronbach’s alpha=0.76).
Behavioral Intentions	A 11-item scale asking participants to report their intentions to make healthier or less healthy eating choices in the future. Each question had 3 different potential answer choices. Responding with the healthiest choice (i.e., grapes) received 1 point, and all other responses receive 0 points. Points were summed to create the total score (possible range 0–11, Cronbach’s alpha= 0.62).
Outcome Expectations	A 9-item scale asking participants to report if they believe statements linking eating behaviors and health outcomes are true or false (example question: I will gain weight if I eat a lot of fatty foods, like potato chips). Participants would respond by saying the statement was true (2 points), mostly true (1 point), mostly false or false (0 points). Points were summed to create the total score (possible range 0–20, Cronbach’s alpha= 0.60).
Social Support44
Social Support for Healthy and Unhealthy Eating	A 14-item questionnaire where youth report the frequency of their caregivers or their friends providing social support for healthy and unhealthy eating behaviors. This questionnaire measures four scales, including: two four-items scales for parent and friend support for healthy eating (example question: How often do your parents/friends give you ideas on how to eat healthier foods?) and two three-item scales measuring parents/friends support for unhealthy eating. Possible responses: never (0), rarely (1), sometimes (2), often (3), very often (4). Scores were summed to create each scale (possible range for healthy eating support scales (0–16), possible range for unhealthy eating support scales (0–12), Cronbach’s alpha’s ranged from 0.70–0.90).
Leadership Skills45
Youth-Leader Skills	Adapted from the youth-leadership literature, this 13-item scale assesses the youth-leaders’ confidence in their abilities to handle common tasks associated with the youth-leader role such as preparing for intervention sessions, problem-solving, and communication. Possible responses were: not at all confident (0), somewhat confident (1), confident (2), and very confident (3). Responses were summed and higher scores indicate higher youth-leader skill levels. (Possible range 0–39, Cronbach’s alpha = 0.94)