SEP and the Impact of Portion Size on Daily Energy Intake

Socioeconomic Position 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. There is some evidence to suggest that individuals with lower socioeconomic position (SEP) intend to eat more from larger portions, suggesting that the effect of portion size on food intake might vary by SEP. However, no study has tested this by measuring actual food intake. This study examines whether reductions to the portion size of components of a main meal will reduce daily energy intake, and whether and how socioeconomic position (higher vs lower) moderates the portion size effect.

In a crossover experiment, participants will be served all meals in the lab on two separate days, with the portion size of main meal components at 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 lunch and dinner, as well as all other meal components (breakfast, dessert, seconds, snacks) will be measured, and any additional food consumed by the participant will be measured using self-report, giving total daily energy intake (kcal).

Study Overview

• Status: Completed
• Conditions: Obesity; Diet, Healthy; Eating Behavior
• Intervention / Treatment: Behavioral: Portion size manipulation

Detailed Description

See attached protocol document.

• Study Type: Interventional
• Enrollment (Actual): 54
• Phase: Not Applicable

Contacts and Locations

Study Locations

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

Participation Criteria

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, aged 18 or over
• Fluent in English
• willing to consume the test foods
• Self report liking of test foods
• BMI between 22.5 - 32.5kg2

Exclusion Criteria:

• taking medication which affects appetite
• currently pregnant
• history of eating disorders
• currently on a diet to lose weight
• food allergies, intolerances or specific dietary requirements (including being vegetarian or vegan)
• participated in 2018 Mood Study
• currently participating in another study where meals are provided

Study Plan

How is the study designed?

Design Details

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

Number of Arms

2

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, breakfast, dessert, snacks).	Behavioral: Portion size manipulation; The intervention was 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, breakfast, dessert, snacks).	Behavioral: Portion size manipulation; The intervention was 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	Total energy (kcal) consumed from breakfast, lunch, dinner, dessert, snackbox, and any self-reported additional foods.	24 hours after intervention administered

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Appetite	Hunger and fullness sensations before and after laboratory-based meals (self-reported on visual analogue scales anchored at 0 'Not at all' and 100 'Extremely')	24 hours after intervention administered
Moderate-vigorous physical activity	Moderate-vigorous physical activity (recorded using wearable activity tracker), operationalised as active minutes/day (logged for activities with a metabolic equivalent of >/3)	24 hours after intervention administered

Collaborators and Investigators

• Sponsor: University of Liverpool
• Collaborators: European Research Council
• Investigators: Principal Investigator: Eric Robinson, PhD, study principle investigator

Study record dates

Study Major Dates

• Study Start (Actual): October 25, 2021
• Primary Completion (Actual): April 7, 2022
• Study Completion (Actual): April 7, 2022

Study Registration Dates

• First Submitted: October 14, 2021
• First Submitted That Met QC Criteria: December 20, 2021
• First Posted (Actual): December 29, 2021

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: socio-economic position; portion size; eating behaviour
• Other Study ID Numbers: 803194

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