Investigating the Effects of Altering Portion Size Reduction Awareness on Compensatory Eating Behaviour

Study Overview
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Brief Summary
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The present study aims to investigate whether energy intake is reduced when participants consume a reduced portion size (15% compared to the 'control' portion), and also to see whether awareness of this reduction affects energy intake.

Detailed Description
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In the present study, all participants will participate in two sessions - the baseline session and the experimental session. In the baseline session, participants will be given ad libitum access to a lunch meal (followed by ad libitum access to dessert), and ad libitum access to a dinner meal (followed by ad libitum access to dessert). Then, after a washout period of between 1-6 weeks, participants will return to complete the experimental session, where they will be randomised to one of three conditions: Condition 1 (control condition): The same as the baseline condition except that the lunch will be of a fixed portion which participants must consume all of - this portion size will be the same amount of food as was consumed in the ad libitum lunch meal in the baseline session (participants will be told that the amount of food served is the same as the amount they consumed in the baseline session). Condition 2 (reduced aware condition): The same as the baseline condition except that the lunch will be of a fixed portion which participants must consume all of - this portion size will be 15% less than the amount of food consumed in the ad libitum lunch meal in the baseline session (participants will be told that the amount of food served has been reduced from the amount they consumed in the baseline session). Condition 3 (reduced unaware condition): The same as the baseline condition except that the lunch will be of a fixed portion which participants must consume all of - this portion size will be 15% less than the amount of food consumed in the ad libitum lunch meal in the baseline session (participants will be told that the amount of food served is the same as the amount they consumed in the baseline session).

Official Title
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Investigating the Effects of Altering Portion Size Reduction Awareness on Compensatory Eating Behaviour

Conditions
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Obesity, Eating Behavior

Intervention / Treatment
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* Behavioral: Portion size manipulation


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: United Kingdom (UK) residents able to visit laboratory on campus in Liverpool, aged ≥ 18 Body Mass Index (BMI) between 18.5 and 32.5 kg/m2 Proficiency in English language Self-report willingness to eat each of the test foods Exclusion Criteria: Current medication use which affects appetite Pregnant Currently or previously diagnosed with an eating disorder Currently on a diet Have any food allergies or intolerances Are vegan

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 60 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Control Condition<br>Participants will be served a lunch - this will be of a fixed portion - this portion size will be the same amount of food as was consumed in the ad libitum lunch meal in the baseline session (participants will be told that the amount of food served is the same as the amount they consumed in the baseline session). | Behavioral: Portion size manipulation<br>* The intervention will be administered via changing portion sizes of foods served to participants. Depending on the condition participants are in, they will be served either a portion size which consists of the amount of food they consumed in the first test session, or a reduced portion size. Within these two reduced portion size conditions, one group of participants will be made aware that their portion size has been reduced, the other will not and instead will be told that this portion size is the same as the amount of food they consumed in the previous session.<br>|
| Experimental: Reduce aware condition<br>Participants will be served a lunch - this will be of a fixed portion - this portion size will be 15% less than the amount of food consumed in the ad libitum lunch meal in the baseline session (participants will be told that the amount of food served has been reduced from the amount they consumed in the baseline session). | Behavioral: Portion size manipulation<br>* The intervention will be administered via changing portion sizes of foods served to participants. Depending on the condition participants are in, they will be served either a portion size which consists of the amount of food they consumed in the first test session, or a reduced portion size. Within these two reduced portion size conditions, one group of participants will be made aware that their portion size has been reduced, the other will not and instead will be told that this portion size is the same as the amount of food they consumed in the previous session.<br>|
| Experimental: Reduced unaware condition<br>Participants will be served a lunch - this will be of a fixed portion - this portion size will be 15% less than the amount of food consumed in the ad libitum lunch meal in the baseline session (participants will be told that the amount of food served is the same as the amount they consumed in the baseline session). | Behavioral: Portion size manipulation<br>* The intervention will be administered via changing portion sizes of foods served to participants. Depending on the condition participants are in, they will be served either a portion size which consists of the amount of food they consumed in the first test session, or a reduced portion size. Within these two reduced portion size conditions, one group of participants will be made aware that their portion size has been reduced, the other will not and instead will be told that this portion size is the same as the amount of food they consumed in the previous session.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Immediate energy intake post-fixed lunch meal | Amount of energy consumed from the lunch dessert | Within 30 minutes after intervention administered | 
| Total delayed post-fixed lunch meal energy intake | Amount of energy consumed from the post-lunch snack box intake, dinner meal, dinner dessert, post-dinner snack box intake, additional energy intake | Within 10 hours after intervention administered | 
| Total post-fixed lunch meal energy intake | Amount of energy consumed from the lunch dessert, post-lunch snack box intake, dinner meal, dinner dessert, post-dinner snack box intake, additional energy intake | Within 10 hours after intervention administered | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Post-lunch snack box intake | Amount of energy consumed from snack box consumed between lunch and dinner | Within 4 hours after intervention administered | 
| Total intake of the ad libitum dinner meal | Amount of energy consumed from the dinner meal | Within 4-5 hours after intervention administered |