SSS and the Impact of Portion Size on Daily Energy Intake

January 9, 2023 updated by: Eric Robinson, University of Liverpool

Subjective Social Status and the Effect of Portion Size Reduction: a 1-day Dietary Behaviour Experimental Study

Reducing food portion size is a potential strategy to reduce energy intake. However, it remains unclear who is most susceptible to the portion size effect (PSE). There are just two studies which have examined the PSE in the context of socioeconomic position (SEP), with mixed findings. In an online trial the PSE on intended consumption of unhealthy snacks was 18-24% larger for participants of lower SEP compared to participants of higher SEP. However, in a recent laboratory study which examined the PSE on total daily energy intake, participants of lower SEP were no more susceptible to the influence of portion size on eating behaviour than participants of higher SEP. Further research is required to elucidate these divergent findings.

There is also an absence of evidence examining the moderating role of subjective social status (SSS) - an individual's perceived standing in society - on the PSE. Given evidence that the subjective experience of social class may be associated with health outcomes, the present study examines whether reductions to the portion size reduces daily energy intake, and whether and how SSS (higher vs lower) moderates the PSE.

In a crossover experiment, participants will be served all meals in the lab on two separate days, with the portion size of main components at breakfast, lunch and dinner manipulated (i.e. smaller on one day vs larger on the other day). All other foods offered are identical. Food intake from the portion-manipulated breakfast, lunch and dinner, as well as all other meal components (non-portion-manipulated sides, dessert, seconds, snacks, etc.) will be measured, to assess total daily energy intake (kcal).

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

See Study Protocol attached.

Study Type

Interventional

Enrollment (Actual)

47

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • United Kingdom
      • Liverpool, United Kingdom, L69 7ZA
        • University of Liverpool

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

Female

Description

Inclusion Criteria:

  • Female
  • UK (United Kingdom) residents, able to visit laboratory in Liverpool
  • Aged 18 or over
  • Fluent in English
  • willing to consume the test foods
  • Self report willingness to eat test foods
  • BMI between 18.5 - 32.5kg2

Exclusion Criteria:

  • participation in our previous study
  • food allergies, intolerances or specific dietary requirements (except vegetarian)
  • taking medication which affects appetite
  • currently pregnant
  • history of eating disorders
  • currently on a diet to lose weight

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Prevention
  • Allocation: Randomized
  • Interventional Model: Crossover Assignment
  • Masking: Single

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Larger portions
the main meal component (lunch/dinner) served to participants in the laboratory, reflecting 100% portion. All other foods are identical across conditions (e.g. sides, seconds, dessert, snacks).
Behavioral: Portion size manipulation
The intervention will be administered via changing portion sizes of foods served to participants.
Experimental: Smaller portions
the main meal component (lunch/dinner) served to participants in the laboratory, reflecting 66% portion (i.e. reduced portion size). All other foods are identical across conditions (e.g. sides, seconds, dessert, snacks).
Behavioral: Portion size manipulation
The intervention will be administered via changing portion sizes of foods served to participants.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Daily energy intake
Time Frame: Time Frame: 24 hours after intervention administered
Total energy (kcal) consumed from breakfast, lunch, dinner, dessert, snackbox, and any self-reported additional foods.
Time Frame: 24 hours after intervention administered

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Energy intake from portion-manipulated foods
Time Frame: Time Frame: 24 hours after intervention administered
Total energy (kcal) consumed from portion-manipulated foods at breakfast, lunch, and dinner
Time Frame: 24 hours after intervention administered
Energy intake from non portion-manipulated foods
Time Frame: Time Frame: 24 hours after intervention administered
Total energy (kcal) consumed from other foods (no portion-manipulation) at breakfast, lunch, dinner, snacks, and self-reported foods.
Time Frame: 24 hours after intervention administered

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

University of Liverpool

Collaborators

European Research Council

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

May 30, 2022

Primary Completion (Actual)

October 12, 2022

Study Completion (Actual)

October 12, 2022

Study Registration Dates

First Submitted

May 26, 2022

First Submitted That Met QC Criteria

May 26, 2022

First Posted (Actual)

June 1, 2022

Study Record Updates

Last Update Posted (Estimate)

January 10, 2023

Last Update Submitted That Met QC Criteria

January 9, 2023

Last Verified

January 1, 2023

More Information

Terms related to this study

Keywords

Other Study ID Numbers

  • 803194 SSS PSE

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

Yes

IPD Plan Description

Study data (anonymised) will be shared on the Open Science Framework (OSF)

IPD Sharing Time Frame

On publication, indefinitely

IPD Sharing Access Criteria

Open website

IPD Sharing Supporting Information Type

  • Study Protocol
  • Statistical Analysis Plan (SAP)

Study Data/Documents

  1. Study Protocol
    Information comments: Protocol on the Open Science Framework (OSF)
  2. Statistical Analysis Plan
  3. Individual Participant Data Set
    Information comments: The study protocol and statistical analysis plan were pre-registered on the OSF prior to starting recruitment. Participant dataset (anonymised) will be made available when results are published.

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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