Reductions to main meal portion sizes reduce daily energy intake regardless of perceived normality of portion size: a 5 day cross-over laboratory experiment



Haynes, Ashleigh, Hardman, Charlotte A ORCID: 0000-0002-0744-6019, Halford, Jason CG ORCID: 0000-0003-1629-3189, Jebb, Susan A, Mead, Bethan R ORCID: 0000-0002-9294-517X and Robinson, Eric ORCID: 0000-0003-3586-5533
(2020) Reductions to main meal portion sizes reduce daily energy intake regardless of perceived normality of portion size: a 5 day cross-over laboratory experiment. International Journal of Behavioral Nutrition and Physical Activity, 17 (1). 21-.

[img] Text
Haynes et al_IJBNPA_AAM.pdf - Author Accepted Manuscript

Download (454kB) | Preview

Abstract

Background Smaller portions may help to reduce energy intake. However, there may be a limit to the magnitude of the portion size reduction that can be made before consumers respond by increasing intake of other food immediately or at later meals. We tested the theoretical prediction that reductions to portion size would result in a significant reduction to daily energy intake when the resulting portion was visually perceived as ‘normal’ in size, but that a reduction resulting in a ‘smaller than normal’ portion size would cause immediate or later additional eating. Methods Over three 5-day periods, daily energy intake was measured in a controlled laboratory study using a randomized crossover design (N = 30). The served portion size of the main meal component of lunch and dinner was manipulated in three conditions: ‘large-normal’ (747 kcal), ‘small-normal’ (543 kcal), and ‘smaller than normal’ (339 kcal). Perceived ‘normality’ of portion sizes was determined by two pilot studies. Ad libitum daily energy intake from all meals and snacks was measured. Results Daily energy intake in the ‘large-normal’ condition was 2543 kcals. Daily energy intake was significantly lower in the ‘small-normal’ portion size condition (mean difference − 95 kcal/d, 95% CI [− 184, − 6], p = .04); and was also significantly lower in the ‘smaller than normal’ than the ‘small-normal’ condition (mean difference − 210 kcal/d, 95% CI [− 309, − 111], p < .001). Contrary to predictions, there was no evidence that the degree of additional food consumption observed was greater when portions were reduced past the point of appearing normal in size. Conclusions Reductions to the portion size of main-meal foods resulted in significant decreases in daily energy intake. Additional food consumption did not offset this effect, even when portions were reduced to the point that they were no longer perceived as being normal in size. Trial registration Prospectively registered protocol and analysis plan: https://osf.io/natws/; retrospectively registered: https://clinicaltrials.gov/ct2/show/NCT03811210.

Item Type: Article
Uncontrolled Keywords: Portion size, Obesity, Norms, Food environment, Food portion, Downsizing
Depositing User: Symplectic Admin
Date Deposited: 30 Jan 2020 14:23
Last Modified: 19 Jan 2023 00:05
DOI: 10.1186/s12966-020-0920-4
Related URLs:
URI: https://livrepository.liverpool.ac.uk/id/eprint/3072705