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

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.

Study Overview

• Status: Recruiting
• Conditions: Obesity; Eating Behavior
• Intervention / Treatment: Behavioral: Portion size manipulation

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 Type: Interventional
• Enrollment (Estimated): 108
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United Kingdom
  • Liverpool, United Kingdom, L69 7ZA
    • Recruiting
    • University of Liverpool
    • Contact: Eric Robinson; Phone Number: +44 (0)151 794 1187; Email: Eric.Robinson@liverpool.ac.uk
    • Principal Investigator: Eric Robinson, PhD

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

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 Plan

How is the study designed?

Design Details

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

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Control Condition; 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; 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.
Experimental: Reduce aware condition; 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; 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.
Experimental: Reduced unaware condition; 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; 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.

What is the study measuring?

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

Collaborators and Investigators

• Sponsor: University of Liverpool

Study record dates

Study Major Dates

• Study Start (Actual): November 1, 2023
• Primary Completion (Estimated): April 30, 2024
• Study Completion (Estimated): April 30, 2024

Study Registration Dates

• First Submitted: October 30, 2023
• First Submitted That Met QC Criteria: November 4, 2023
• First Posted (Actual): November 7, 2023

Study Record Updates

• Last Update Posted (Actual): November 29, 2023
• Last Update Submitted That Met QC Criteria: November 28, 2023
• Last Verified: November 1, 2023

More Information

Terms related to this study

• Other Study ID Numbers: Portion size reduction study

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: An anonymised data set will be published on the open science framework for anyone to access.
• IPD Sharing Time Frame: Data will be available after data collection has finished, this will be available indefinitely.
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; ANALYTIC_CODE

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No