The Beneficial Effects of Protein-rich, Afternoon Snacks on Appetite Control, Satiety, and Reward-driven Eating Behavior in Young People

Forty adolescents will participate in the following randomized crossover-design study. Prior to the start of the study, the participants will be asked to document their habitual breakfast, lunch, and afternoon snack times. The snack patterns and associated testing days will be scheduled so that each participant consumes the afternoon snack (or refrains from snacking) 3 hours after lunch; however, the time of day when this occurs is based on the participant's previous, habitual snack time. Once this is determined, each participant will randomly acclimate to the following snack pattern for 3 consecutive days: 1) Higher Protein Soy-based Snacks (250 kcal; 40% Protein; 40% Carbohydrates; 20% Fat); 2) Typical, Low Protein Snacks (5% Protein; 50% Carbohydrates; 45% Fat); and 3) No Snack.

On day 4, the participants will consume a standard breakfast, at home, and lunch, at school, and will come in to our facility 1 hour prior to their habitual snack time. The participants will be placed in a window-less, comfortable room, void of all time cues. They will be informed that they will remain in this room for the next 6 hours. The participants will begin the testing day by completing baseline questionnaires assessing appetite, satiety, mood, and cognitive function. A brain scan will be completed using functional magnetic resonance imaging (fMRI) to identify brain activation patterns in response to food stimuli. Following the fMRI scan, the respective snack will be given to the participants; they will have 15 minutes to eat the snack. A second fMRI scan will then be performed. The participants will continue to complete the previous questionnaires until they voluntarily choose to eat. At this time, the volunteers will be presented with an 'all you can eat' snack buffet. They will be permitted to eat as much or as little as they would like to eat over the next 3-hour period. The participants will remain in the facility until the full 8-hour testing day is completed, regardless of when they requested to eat. Following the 6 hours, the participants will be permitted to leave the facility.