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.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
TRIPLE
Enrollment
37
250 kcal; 40% Protein; 40% Carbohydrate; 20% Fat
5% Protein; 50% Carbohydrates; 45% Fat
University of Missouri-Columbia
Columbia, Missouri, United States
Time to Dinner Request
The participants will be asked whether they would like to request a dinner buffet throughout the 5 h post-snack period. When the response is "Yes, I want to eat right now", the time from snack consumption will be recorded.
Time frame: 1 Day
Appetite Questionnaires
Computerized questionnaires, assessing perceived sensations of appetite will be completed throughout the testing days. The questionnaires contain visual analog scales incorporating a 100 mm horizontal line rating scale for each response. The questions are worded as "how strong is your feeling of" with anchors of "not all" (scored as 0 out of 100) to "extremely" (scored as 100 out of 100). The following questions will be incorporated as 1 composite score ((Questions 1 + 3 + 4 - 2)/4) multiplied by the 300 minutes (a max of 30,000 mm\*min and a minimum of -30,000 mm\*min): 1. How strong is your feeling of hunger? 2. How strong is your feeling of being full? 3. How strong is your desire to eat? 4. How much food could you consume right now? The Adaptive Visual Analog Scale Software (Neurobehavioral Research Laboratory and Clinic; San Antonio, TX) was used for these assessments.
Time frame: 0 min, + 30 min, +60 min, +90 min, +120 min, +150 min, +180 min, +210 min, +240 min, +270 min, +300 min
Snack Palatability and Perception Questionnaires
Computerized questionnaires, assessing snack palatability and perceptions of the snack will be completed during screening and after the first and last bite of each snack during the acclimation and testing days. The questionnaires contain visual analog scales incorporating a 100 mm horizontal line rating scale for each response. The questions are worded as "how strong is your feeling of" with anchors of "not all" (scores 0 out of 100) to "extremely" (scores 100 out of 100). The questions assess snack appearance, smell, flavor, texture (feel), liking. The Adaptive Visual Analog Scale Software (Neurobehavioral Research Laboratory and Clinic; San Antonio, TX) was used for these assessments.
Time frame: 5 min
Attention & Memory Questionnaires
Cognitive function will be assessed immediately before (-30 min) and 60 min post-snack using the lap-top based Cantab® computerized assessment system. This program consisted of a core battery of tests grouped into main categories including 1) Working Memory; 2) Reasoning; 3) Executive Function; 4) Reaction Time; 5) Sustained Attention; 6) Cognitive Flexibility; and 7) Processing Speed. This program has been used in our previous breakfast studies with success. A greater raw score for working memory, reasoning, executive function, sustained attention, and cognitive flexibility is considered to be greater performance. A lower score for reaction time and processing speed is considered to be greater performance. The raw scores are determined by Cantab® computerized assessment system. Therefore, maximum and minimum values for each test are unknown.
Time frame: 90 min
Mood-state Questionnaires
Indices of mood state will be assessed immediately before and 60 min post-snack using the on-line, Profile of Mood States, 2nd Edition (POMS2). This program consisted of a core battery of tests with the following sub-categories 1) Tension; 2) Depression; 3) Anger; 4) Vigor; 5) Fatigue; 6) Confusion; and 7) Friendliness. Outcomes are scored as a T-score which could be a minimum of zero with no upper limit. A lower score represents a more positive mood state and a higher score represents a more negative mood state.
Time frame: -30 min, +60 min
Energy Intake
Post-snack energy intake will be assessed through ad libitum dinner and snacking assessments. The ad libitum dinner will contain approximately 2,000 kcal and will consist of a chicken, rice, and stir-fry meal, chips, chocolate mints, ice tea, and water. The dinner meal will be consumed in the testing facility. The participants will be instructed to eat as much as or as little as they choose over a 30 min period. All contents will be weighed before the dinner and any remains will be re-weighed afterwards to determine the type and quantity of foods consumed. The ad libitum evening snacks will contain 3,000 kcal and will include common snack foods. After the testing day is complete, the participants will take the snack packout home and consume any of the foods he/she chooses until going to bed. All contents will be weighed before the packout and any remains will be re-weighed afterwards to determine the type and quantity of foods consumed.
Time frame: +300 min, 24 h
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