For some time, I’ve believed we can eat less (or more) by manipulating the size of the plates/bowls that we serve our food in. For example, by placing your pesto pasta on a larger plate, you would perceive it as a smaller portion. However, as the plate size decreases, your brain is ‘hacked’ into thinking your pasta portion has increased.
This theory originated from Joseph Delboeuf, who came up with the Delboeuf illusion in 1865. When you place two black circles of the same size next to each other, one surrounded by a large ring, and one surrounded by a small ring, the black circle surrounded by the large ring is perceived as smaller.
One study indicated that humans misjudge portion sizes of meals when presented in different contexts. Participants were presented with images of different portion sizes of food using the same plate size. The plate rims were manipulated by size, colour, and pattern. Food sample was also manipulated. The researchers concluded that the illusion effect was present in this study. When participants viewed plates with wider and coloured rims, they overestimated the amount of food that was on the plate. They also noted that food variety had no effect on this illusion. These results suggest that plate design can have important implications towards weight loss and management strategies.
What if you added appetite into this equation?
It is apparent to most of us that hunger has a strong influence on how we see food (duh!). Two researchers from Israel conducted a study examining whether depriving people of food affects the Delboeuf illusion. Participants were divided into two conditions: food deprivation and non-deprivation. They were presented with two pizzas on circular wooden blocks: a standard pizza on a wooden block and another pizza (size is manipulated) on a significantly larger wooden block. During the experiment, participants were asked to choose the larger pizza on the display. It turns out that when participants were deprived of food, they are less sensitive to the portion size illusion. It could be that they were less distracted by the surrounding context of the pizza presented. These findings imply that we need to take into account confounding factors, such as motivation, on how food is perceived by the human eye.
Perhaps dieting by tricking our minds into thinking that we are eating less therefore not a reliable and long-term solution, especially when we were are feeling hungry…
