SSS and the Impact of Portion Size on Daily Energy Intake

Study Overview
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Brief Summary
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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).

Detailed Description
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See Study Protocol attached.

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

Conditions
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Obesity, Diet, Healthy, 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: 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

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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Female

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: Prevention
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Larger portions<br>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<br>* The intervention will be administered via changing portion sizes of foods served to participants.<br>|
| Experimental: Smaller portions<br>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<br>* The intervention will be administered via changing portion sizes of foods served to participants.<br>|

What is the study measuring?
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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. | Time Frame: 24 hours after intervention administered | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Energy intake from portion-manipulated foods | 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 | 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 | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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portion size, socio-economic position, eating behaviour