A pilot and feasibility study was conducted by ChildObesity180 at the Friedman School of Nutrition Science and Policy at Tufts University, with data collection taking place at two large national restaurant chains. Stand-alone QSRs (n = 15) and malls with food courts (n = 2) containing the selected QSRs were approached to participate. Locations were based on proximity to the Greater Boston area, with an emphasis on socioeconomically diverse settings. Two stand-alone QSRs (both from the same QSR chain [“QSR Chain 1”]) and one mall with two QSRs in the food court (QSR Chain 1 and a second chain [“QSR Chain 2”]) agreed to participate (hereafter referred to as “QSRs”). This study was approved by the Tufts University Institutional Review Board.
Participants
Participants were parents or legal guardians (herein referred to as “parents”) who were at least 18 years old and purchasing food for a child between the ages of 5-10 years for onsite consumption. A total of n = 55 parents were recruited (47% of the eligible parents approached). Written informed consent was not required, but research assistants explained all relevant study information to participants and provided them with a participant information document.
Recruitment and plate waste methodology
Data were collected on 10 weekend days over three months (January through March 2015), between 11 am and 8 pm. All adults with a child in the restaurant were approached at one of two time points: (1) while waiting in line to order but after finalizing their meal selections (to minimize influencing meal choices); or (2) immediately after placing their order. After confirming eligibility, recruited participants provided their sales receipt. Additionally, at the end of the meal, participants provided any leftover foods from the child’s meal. If more than one child with the parent met the age criterion, the child with the closest birthday to the date of data collection was chosen to ensure random selection. At QSR locations with self-serve soda fountains (n = 2), the child’s drink cup was weighed after ice was placed in it and after the drink was poured. Food sharing was discouraged, but if sharing did occur, participants reported the amount shared at the end of the meal.
At the end of the meal, parents provided all remaining foods and containers/wrappers (including condiment packets) from the child’s meal. Additionally, parents described all of the foods ordered for the child, including the size and any modifications to the menu items, and completed a survey which included demographic information for both the parent and child. If a parent wanted to bring remaining foods home, leftovers were weighed on site (n = 12 food items). Otherwise, foods were brought back to the lab in sealed bags for weighing. Foods were weighed in grams using food scales (OXO 1130800, OXO Company).
Two samples of every food ordered by the participants were purchased to obtain pre-consumption weights (for fountain sodas, the weights of the ice and drink were replicated). Consumption was calculated using the formula:
$$ \frac{\mathrm{Average}\ \mathrm{preweight}\ \mathrm{of}\ \mathrm{the}\ \mathrm{food}\ \left[\mathrm{based}\ \mathrm{on}\ 2\ \mathrm{samples}\right]\hbox{-} \mathrm{Postweight}\ \mathrm{of}\ \mathrm{the}\ \mathrm{food}}{\mathrm{Average}\ \mathrm{preweight}\ \mathrm{of}\ \mathrm{the}\ \mathrm{food}\ \left[\mathrm{based}\ \mathrm{on}\ 2\ \mathrm{samples}\right]} \times 100 $$
For shared items, parents were asked to estimate the percent or quantify the number of an item consumed by the child (e.g., ten fries); when a number was provided, this quantity from the pre-weight sample was weighed to estimate the post-consumption weight. The percentage consumed calculated for each food item was multiplied by the stated nutrient contents available on the QSRs’ websites to determine nutrients consumed for that food item. Nutrients consumed for each food item (i.e., entrée, beverage, side, condiments, and dessert) were summed to determine the overall nutrients consumed by the child.
The nutrients from the meals were compared with the National Restaurant Association’s Kids LiveWell standards for children’s meals which require at least two healthy components (fruit, vegetable, whole grain, lean protein, and/or lower-fat dairy [1% or skim]) and include limits for calories (≤600 kcal), total fat (≤ 35% of calories) saturated fats (≤ 10% of calories), trans fat (≤ 0.5 g), sodium (≤ 770 mg), and sugar (≤ 35% of calories) [13].
Bomb calorimetry methodology
Bomb calorimetry was used to evaluate the accuracy of the QSR-stated energy content of foods, with methods based on those previously reported [10, 11]. Twenty unique foods were randomly selected from foods ordered by participants (n = 10 foods from QSR Chain 1 and n = 10 foods QSR Chain 2) for energy content analyses using a bomb calorimeter, which is typically accurate to a mean (SD) of -1.9% (0.3%) [10]. Only entrées, side dishes, beverages, and desserts were analyzed; condiments were analyzed only if they were included as part of a meal (e.g., a hamburger with ketchup). Food samples were placed in sealed bags and frozen. Pre-consumption samples (two samples of each food combined) were analyzed to assess the accuracy of the QSR-stated energy content of the foods, and in secondary analyses, the corresponding post-consumption samples were analyzed to evaluate the accuracy of plate waste methodology in QSRs. After weighing, samples were blended to a homogenous consistency, freeze-dried (Virtis Benchmark 1000 Lyophilizer, Virtis Co, Gardiner, NY), ground into a fine powder, and pressed into pellets of approximately 1 g each. Gross energy was determined using an Isoperibol Bomb Calorimeter (Parr model 1261, Parr Instrument Co, Moline, IL), with benzoic acid (Benzoic Acid 1 g pellets, Parr Instrument Co, Moline, IL) used as the standard for calibration. Total energy content for each food sample was determined by multiplying the total weight from the dried foods by the mean heat of combustion from the samples (accounting for duplicate samples where applicable).
Because bomb calorimetry determines the gross energy content of foods, while the stated energy is a metabolizable energy estimation (i.e., the gross energy adjusted for obligatory energy losses in urine and feces), QSR-stated energy was converted to gross energy equivalents using the formula: gross energy = (fat [in grams]) × 9.4) + (protein [in grams]) × 5.65) + (total carbohydrate [in grams]) × 4.15) [10, 14].
Of the 20 pre-consumption samples, three were later excluded. One was determined to be a non-caloric diet beverage. Two other beverage samples were served by employees at QSRs that did not have a self-serve soda fountain and contained substantial levels of ice (but the exact quantity was unknown) while the QSR-stated energy information was for a beverage without ice. Therefore n = 17 pre-consumption samples were analyzed. Seven corresponding post-consumption food items were also analyzed.
Analyses
Descriptive statistics were used to examine QSR recruitment and participant characteristics. T-tests were used to determine differences in the calories, total fat, percent of calories from total fat, saturated fat, percent of calories from saturated fat, trans fat, sodium, fiber, sugar, and percent of calories from sugar for the foods ordered and consumed from the standard versus children’s menu. Child age and sex were not significant confounders when examining selection or consumption and therefore were not controlled for in analyses. Comparisons of the QSR-stated energy values with those determined using bomb calorimetry techniques were conducted using paired t-tests. Analyses were performed in 2015 using SAS statistical software (version 9.4, SAS Institute Inc).