Bottomless Bowls: Why Visual Cues of Portion Size May Influence Intake

Objective: Using self‐refilling soup bowls, this study examined whether visual cues related to portion size can influence intake volume without altering either estimated intake or satiation.

Research Methods and Procedures: Fifty‐four participants (BMI, 17.3 to 36.0 kg/m2; 18 to 46 years of age) were recruited to participate in a study involving soup. The experiment was a between‐subject design with two visibility levels: 1) an accurate visual cue of a food portion (normal bowl) vs. 2) a biased visual cue (self‐refilling bowl). The soup apparatus was housed in a modified restaurant‐style table in which two of four bowls slowly and imperceptibly refilled as their contents were consumed. Outcomes included intake volume, intake estimation, consumption monitoring, and satiety.

Results: Participants who were unknowingly eating from self‐refilling bowls ate more soup [14.7 ± 8.4 vs. 8.5 ± 6.1 oz; F(1,52) = 8.99; p < 0.01] than those eating from normal soup bowls. However, despite consuming 73% more, they did not believe they had consumed more, nor did they perceive themselves as more sated than those eating from normal bowls. This was unaffected by BMI.

https://onlinelibrary.wiley.com/doi/full/10.1038/oby.2005.12