If you think serving food on a smaller plate can trick your brain into eating less, think twice. According to a study, when people are food deprived, they are more likely to consider a portion size accurately, irrespective of how it’s served. The new study debunks the popular diet trick based on the Delbouef illusion that predicts people will identify sizes differently when they are placed within a larger or smaller object.
“Plate size doesn’t matter as much as we think it does,” said Tzvi Ganel, from the Ben-Gurion University (BGU) in Beersheba, Israel. “Even if you’re hungry and haven’t eaten, or are trying to cut back on portions, a serving looks similar whether it fills a smaller plate or is surrounded by empty space on a larger one,” Ganel added, in the paper published in the journal Appetite.
In the study to examine the way food deprivation affects perception of food in different contexts, the researchers found that people who had not eaten for at least three hours were more likely to identify the proportions of pizza placed on larger and smaller trays correctly than people who had eaten recently. However, this only worked when it applied to food. Both groups were similarly inaccurate when asked to compare the size of black circles and hubcaps placed within different sized circles.
This indicates that hunger stimulates stronger analytic processing that is not as easily fooled by the illusion, the researchers said. “Over the last decade, restaurants and other food businesses have been using progressively smaller dishes to conform to the perceptual bias that it will reduce food consumption,” Ganel said. “This study debunks that notion. When people are hungry, especially when dieting, they are less likely to be fooled by the plate size, more likely to realise they are eating less and more prone to overeating later.”