"This snack is too small - I'll take a different one": Quantifying 'norm' and 'choice' boundaries to inform effective portion-reduction strategies

Roya O Shahrokni*, Danielle Ferriday, Sonia Miguel, Aurelie L. Laurent, Jeffrey M. Brunstrom

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

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Abstract

Previous research suggests that portion sizes can be categorised as 'normal' or 'abnormal' and that reduced portions which are still categorised as normal do not promote compensatory responses in intake. However, a critical question remains - will consumers choose a reduced portion product from among standard portion competitors? For the first time, we explore the effects of portion reduction on food choice. Participants (N = 45) categorised 20 different portions (range 40-420 kcal) of five snacks as normal or abnormal (to quantify individual 'norm boundaries' for each food) and rated their desire to eat each snack. Using a 2-alternative forced choice hypothetical task, we then calculated a 'choice boundary' by offering smaller portions of their most-desired snack (range 40-240 kcal) alongside standardised portions (240 kcal) of the less-desired foods. Boundaries were derived using probit analysis (choice boundary mean = 185.8 kcal, SD = 54, norm boundary mean = 127.3 kcal, SD = 49.5) and these deviated significantly (p < .01, d = 0.98, mean difference = 58.0 kcal, SD = 59.1). Critically, this shows that only a small reduction - where the product is still considered normal - can nudge a consumer to select an alternative. Choice boundaries were also affected by differences in desire to eat; when two foods were desired to a similar degree, only minor reductions in the size of the favourite food elicited a switch in choice. Together, these findings indicate that portion reduction can also influence food choice, highlighting the importance of measuring choice boundaries before reformulating commercial products.

Original languageEnglish
Article number105886
Pages (from-to)105886
JournalAppetite
Volume171
Early online date22 Dec 2021
DOIs
Publication statusPublished - 1 Apr 2022

Bibliographical note

Funding Information:
Ethical approval for this experiment was granted by the University of Bristol Faculty of Life Sciences Human Research Ethics Committee (ethical approval ID: 27061989707). All participants provided informed consent before taking part in the experiment as well as informed final consent after being debriefed.This work was supported by a Biotechnology and Biological Sciences Research Council Doctoral Training Partnership with Mondel?z International Limited awarded to ROS (BB/S506850/1). The ideas relating to portion size breakpoints were developed in part during the preparation of a grant funded by BBSRC DRINC (BB/L02554X/1). JMB is supported by the NIHR Biomedical Research Centre at University Hospitals Bristol and Weston NHS Foundation Trust and the University of Bristol. The views expressed in this publication are those of the author and not necessarily those of the NHS, NIHR, or the Department of Health and Social Care.

Funding Information:
This work was supported by a Biotechnology and Biological Sciences Research Council Doctoral Training Partnership with Mondelēz International Limited awarded to ROS ( BB/S506850/1 ). The ideas relating to portion size breakpoints were developed in part during the preparation of a grant funded by BBSRC DRINC ( BB/L02554X/1 ). JMB is supported by the NIHR Biomedical Research Centre at University Hospitals Bristol and Weston NHS Foundation Trust and the University of Bristol . The views expressed in this publication are those of the author and not necessarily those of the NHS, NIHR, or the Department of Health and Social Care.

Publisher Copyright:
© 2022 The Authors

Structured keywords

  • Nutrition and Behaviour

Keywords

  • Desire to eat
  • Energy intake
  • Food choice
  • Portion size
  • Reformulation

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