New research appears to debunk the popular myth that serving food on a smaller plate will trick the brain and help us to eat less.
Carried out by researchers at Ben-Gurion University of the Negev (BGU), Israel, the two new studies investigated the popular diet trick of serving food on a smaller plate, which is based on the Delboeuf illusion.
The Delboeuf illusion predicts people will identify sizes differently when they are placed within a larger or smaller object. For example, the classic experiment shows that a black circle is perceived as smaller when it is placed in a larger circle than when it is placed in a smaller one.
The researchers carried out two experiments with a total of 131 participants to see if being hungry affected the perception of food in different contexts.
They found that when people are food-deprived, they’re more likely to identify a portion size accurately, no matter how it is served, with the participants who hadn’t eaten for at least three hours more likely to correctly identify the proportions of pizza placed on both larger and smaller trays than people who had eaten recently.
In addition, the researchers also found that the two groups were only able to identify the sizes correctly when it came to food. When in another test participants were asked to compare the size of black circles and hubcaps placed within different sized circles, both groups were similarly inaccurate.
The team commented that the findings indicate that hunger stimulates stronger analytic processing that is not as easily fooled by the illusion.
“Plate size doesn’t matter as much as we think it does,” says Dr Tzvi Ganel, head of the Laboratory for Visual Perception and Action in BGU’s Department of Psychology.
“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.”
“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,” added Ganel.
“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.”