What is eaten when all of the foods at a meal are served in large portions?

Abstract

Portion size affects intake, but when all foods are served in large portions, it is unclear whether every food will be consumed in greater amounts. We varied the portion size (PS) of all foods at a meal to investigate the influence of food energy density (ED) on the PS effect as well as that of palatability and subject characteristics. In a crossover design, 48 women ate lunch in the laboratory on four occasions. The meal had three medium-ED foods (pasta, bread, cake) and three low-ED foods (broccoli, tomatoes, grapes), which were simultaneously varied in PS across meals (100%, 133%, 167%, or 200% of baseline amounts). The results showed that the effect of PS on the weight of food consumed did not differ between medium-ED and low-ED foods (p < 0.0001). Energy intake, however, was substantially affected by food ED across all portions served, with medium-ED foods contributing 86% of energy. Doubling the portions of all foods increased meal energy intake by a mean (±SEM) of 900 ± 117 kJ (215 ± 28 kcal; 34%). As portions were increased, subjects consumed a smaller proportion of the amount served; this response was characterized by a quadratic curve. The strongest predictor of the weight of food consumed was the weight of food served, both for the entire meal (p < 0.0001) and for individual foods (p = 0.014); subject characteristics explained less variability. Intake in response to larger portions was greater for foods that subjects ranked higher in taste (p < 0.0001); rankings were not related to food ED. This study demonstrates the complexity of the PS effect. While the response to PS can vary between individuals, the effect depends primarily on the amounts of foods offered and their palatability compared to other available foods.

Trial registration: ClinicalTrials.gov NCT02369588.

Keywords: Disinhibition; Energy density; Energy intake; Food intake; Palatability; Portion size.

Copyright © 2016 Elsevier Ltd. All rights reserved.

Figures

Fig. 1

Mean (± SEM) food intake (A) and energy intake (B) of 48 women who were served a meal of six foods that were varied in portion size. Three of the foods were low in energy density (ED) and three were medium in ED. Means for the same outcome marked with different letters are significantly different according to a mixed linear model with repeated measures (p<0.02).

Fig. 2

Mean intakes by weight (± SEM) for individual foods and for the entire meal served to 48 women. The mean curves of food intake in response to increases in the portion served were modeled by a random coefficient analysis, in which individual trajectories were allowed to vary across subjects. The weight consumed of the entire meal and of each food was significantly influenced by the weight served (p<0.0001). Intake curves for each food also differed significantly from each other (p<0.014). The dotted line shows the potential maximum intake (consumption of the entire amount served).

Fig. 3

Mean food intake curves for six foods according to their taste ranking at discharge, along with scatterplots of individual food intakes for 46 women. The mean curves of food intake in response to increases in the portion served were modeled by a random coefficient analysis, in which trajectories were allowed to vary across subjects. Subject rankings of food taste significantly affected intake of the foods as portion sizes were increased (p<0.0001). Taste rankings with different superscripts differ significantly in the linear coefficient of the intake curve (p<0.03). The curve for Rank 1 shows the mean intake of the food ranked as best-tasting, which differed across individuals. The dotted line shows the line of potential maximum intake (consumption of the entire amount served).