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

Not Applicable

Completed

• Conditions: Eating Behavior; Obesity
• Interventions: Behavioral: Portion size manipulation

• Registration Number: NCT06119295
• Lead Sponsor: University of Liverpool

Brief Summary

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

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).

Study Timeline

• Study First Submitted: 2023-10-30
• Status Verified: 2023-11
• Study Start: 2023-11-01
• Study First Submitted QC: 2023-11-04
• Study First Posted: 2023-11-07
• Primary Completion: 2024-05-16
• Study Completion: 2024-05-16
• Last Update Submitted: 2024-12-13
• Last Update Posted: 2024-12-18

Recruitment & Eligibility

• Status: COMPLETED
• Sex: All
• Target Recruitment: 108

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

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
Reduce aware condition	Portion size manipulation	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).
Reduced unaware condition	Portion size manipulation	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).
Control Condition	Portion size manipulation	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).

Primary Outcome Measures

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

Secondary Outcome Measures

Name	Time	Method
Total intake of the ad libitum dinner meal	Within 4-5 hours after intervention administered	Amount of energy consumed from the dinner meal
Post-lunch snack box intake	Within 4 hours after intervention administered	Amount of energy consumed from snack box consumed between lunch and dinner

Trial Locations

Locations (1)

University of Liverpool; 🇬🇧 Liverpool, United Kingdom