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| Name | Class |
|---|---|
| European Research Council | OTHER |
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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).
See Study Protocol attached.
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| Larger portions | Experimental | 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). |
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| Smaller portions | Experimental | 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). |
|
| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| Portion size manipulation | Behavioral | The intervention will be administered via changing portion sizes of foods served to participants. |
|
| 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 |
| 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 |
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Inclusion Criteria:
Exclusion Criteria:
Identify as female
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| Name | Affiliation | Role |
|---|---|---|
| Eric Robinson, PhD | University of Liverpool | Principal Investigator |
| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| University of Liverpool | Liverpool | L69 7ZA | United Kingdom |
| PubMed Identifier | Type | Citation | Retractions |
|---|---|---|---|
| 37101143 | Derived | Langfield T, Clarke K, Marty L, Jones A, Robinson E. Socioeconomic position and the influence of food portion size on daily energy intake in adult females: two randomized controlled trials. Int J Behav Nutr Phys Act. 2023 Apr 27;20(1):53. doi: 10.1186/s12966-023-01453-x. |
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| ID | Type | URL | Comment |
|---|---|---|---|
| Study Protocol | View IPD |
Study data (anonymised) will be shared on the Open Science Framework (OSF)
On publication, indefinitely
Open website
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| ID | Term |
|---|---|
| D005247 | Feeding Behavior |
| D009765 | Obesity |
| ID | Term |
|---|---|
| D001522 | Behavior, Animal |
| D001519 | Behavior |
| D050177 | Overweight |
| D044343 | Overnutrition |
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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 |
Protocol on the Open Science Framework (OSF) |
| Statistical Analysis Plan | View IPD |
| Individual Participant Data Set | View IPD | 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. |
| D009748 |
| Nutrition Disorders |
| D009750 | Nutritional and Metabolic Diseases |
| D001835 | Body Weight |
| D012816 | Signs and Symptoms |
| D013568 | Pathological Conditions, Signs and Symptoms |