Less or More on the Plate: The Impact of Plate Size and Form on Portion Estimation

Objective: This study aimed to investigate how plate size and form affect perceived portion size and expected satiety, with a view toward informing low-cost, visually guided obesity prevention strategies. “Visual fullness,” defined as the perceived occupied area of food on the plate, was evaluated as a key cognitive cue influencing expected satiety.Methods: A cross-sectional online survey was conducted between April and June 2024 with 402 adults (mean age 27.9 ± 7.9 years). Five commonly consumed foods (spinach, bulgur pilaf, stir-fry, pasta, and soup) were presented via standardized food photographs on plates of varying sizes and shapes. Participants estimated portion weight (grams) and rated expected satiety using a 10 cm visual analogue scale (VAS). Plate types included dessert plates of three sizes and ten diverse dish designs. Statistical analyses were performed using one-way ANOVA with post hoc Tukey tests for group comparisons. A key result showed that plate size significantly influenced expected satiety for spinach (F(2,1203)=3.759, p=0.024).Results: Plate size significantly influenced satiety perception for spinach (p=0.024), with the large dessert plate (LDP) yielding higher VAS scores than the small plate (SDP). Plate shape significantly affected both perceived weight and satiety for spinach, bulgur pilaf, pasta, and soup (all p