Participants were asked to consume their lunch ad libitum from a multiple-item buffet test meal on two separate days, scheduled at least two days apart. Children were randomized to complete either the “normal” meal (at which they were told to “eat as much as you would at a normal meal”) or the “binge” meal (during which they were instructed to “let yourself go and eat as much as you want”) first. Participants were instructed to adhere to an overnight fast initiated at 10:00pm the night before each test meal visit. At each test meal day, participants were instructed to consume an entire standard breakfast consisting of 288 kcal (240 mL apple juice, 1 English muffin, and 6 g butter) at 8:40am. Following the breakfast, each subject remained at the NIH, participating in sedentary activities (e.g., playing computer games, reading, doing arts and crafts, etc.) and was observed to ensure there was no food intake until the afternoon test meal.
At 2:30pm, each child was presented with a 9,835 kcal buffet test meal (3 (link)) with individual items that varied in macronutrient composition (12% protein, 51% carbohydrate, 37% fat across all foods) and contained a wide assortment of foods (Table 1). When each child entered the room containing the buffet, the following tape-recorded instruction was played for the normal meal: “Eat as much as you would at a normal meal;” and for the binge meal, “Let yourself go and eat as much as you want.” Participants were then left alone in the room containing the buffet to eat ad libitum. During the test meals, children viewed pre-taped episodes of a television show with commercials removed. Episodes were pre-viewed so that none involved food, eating, shape, or weight-related topics. Participants were instructed to open the room door when they were finished eating. Time spent eating was measured from the time the investigator left the room to the time the participant opened the door after eating. The amount of each food and beverage consumed was measured using the differences in weight of each food item before and after the meal. Energy content and nutrient composition for each food was determined according a metabolic diet study management system that uses the USDA Nutrient Database for Standard Reference, Release 16 (Viocare Technologies, Inc., Princeton, NJ), as well as nutrient information supplied by food manufacturers.
Immediately before, and again, after each test meal, participants completed the psychometrically sound, State Form of the State-Trait Anxiety Inventory for Children (STAIC) (29 ) which measures anxiety “right now, at this very moment.” They also completed the well-validated Brunel Mood Scale (BRUMS) (30 (link)), which measures present mood state and generates six subscales pertaining to Anger, Confusion, Depression, Fatigue, Tension, and Vigor.