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

The purpose of this study is to examine the effects of normal vs. protein-rich afternoon snacks on appetite control, satiety, and reward-driven eating (particularly in the evening) in young people. Indices of attention and mood will also be assessed.

Study hypotheses include the following:

1. The consumption of a high-protein, soy-rich afternoon snack will lead to significant improvements in appetite control and satiety, reductions in food motivation and reward, and will delay the drive to eat in normal to overweight young people.
2. The consumption of a high-protein, soy-rich afternoon snack will lead to reduced unhealthy, evening snacking, particularly on foods high in fat and/or sugar, in normal to overweight young people.
3. The daily consumption of a high-protein, soy-rich afternoon snack will lead to significant improvements in afternoon alertness, concentration, fatigue, and well-being in normal to overweight 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.

Eligibility Criteria:
Inclusion Criteria:

* Age range 13-19 years
* Normal to overweight (BMI: 50-85th percentile for BMI for age or BMI: 18-29.9 kg/m2)
* No metabolic, psychological, or neurological diseases/conditions
* Not currently or previously on a weight loss or other special diet (in the past 6 months)
* Not clinically diagnosed with an eating disorder
* Habitually eat (i.e., at least 5 times/week) breakfast between 7:00-9:00 am, lunch between 11:00 am-1:00 pm, an afternoon snack between 2:00-4:00 pm, and dinner
* No food allergies or intolerances to soy products
* Rates the overall liking of the study snack foods higher than "Neither Like nor Dislike" on the screening palatability questionnaire
* Right handed

Exclusion Criteria:

* Age 12 years or younger, or 20 years or older
* Underweight or Obese (below 50th or above 85th percentile for BMI for age, or BMI below 18 or above 29.9 kg/m2)
* Any metabolic, psychological, or neurological diseases/conditions
* Currently or previously on a weight loss or other special diet (in the past 6 months)
* Clinically diagnosed with an eating disorder
* Does not habitually eat (i.e., at least 5 times/week) breakfast between 7:00-9:00 am, lunch between 11:00 am-1:00 pm, an afternoon snack between 2:00-4:00 pm, and dinner
* Food allergies or intolerances to soy products
* Does not rate the overall liking of the study snack foods higher than "Neither Like nor Dislike" on the screening palatability questionnaire
* Not right handed