SSS and the Impact of Portion Size on Daily Energy Intake

University of Liverpool

Status: Completed

Conditions: Eating Behavior; Obesity; Diet, Healthy

Treatments: Behavioral: Portion size manipulation

Study type: Interventional

Funder types: Other

Identifiers

NCT05399836

803194 SSS PSE

Details and patient eligibility

About

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).

Full description

See Study Protocol attached.

Enrollment: 47 patients

Sex: Female

Ages: 18+ years old

Volunteers: Accepts Healthy Volunteers

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

Trial design

Primary purpose: Prevention

Allocation: Randomized

Interventional model: Crossover Assignment

Masking: Single Blind

---

47 participants in 2 patient groups

Larger portions

Experimental group

Description:

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).

Treatment:

Behavioral: Portion size manipulation

Smaller portions

Experimental group

Description:

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).

Treatment:

Behavioral: Portion size manipulation