Using smaller plates to trick yourself into eating less? Popular dieting trick does NOT work as hunger always helps us identify portion sizes, say scientists

  • When people are hungry, they are able to accurately identify portion sizes
  • The new study debunks the popular diet trick based on the Delbouef illusion
  • This predicts people identify portions as larger when placed on smaller plates

Using a smaller plate to trick yourself into feeling satisfied with a smaller portion does not work, new research has revealed.

Scientists say when people are hungry, they are able to accurately identify food portion sizes – no matter how the meal is presented or served.

The latest findings debunk a hugely-popular diet trick based on the Delbouef illusion that says people identify portions as larger if they are placed on a smaller plate.

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Scientists say that when people are hungry, they are able to identify food portion accurately, no matter how it is served (stock image)

Scientists say that when people are hungry, they are able to identify food portion accurately, no matter how it is served (stock image)

The Delboeuf illusion is a visual illusion whereby a dot surrounded by a large ring is typically perceived to be smaller than the same-sized dot surrounded by a small ring.

This optical trick works because the human brain judges the size of the dot based on the context of the outer ring.

Until now, it was thought the same optical illusion could be applied to plates.

The theory goes that using a smaller plate tricks you into thinking you're enjoying more food than is on your plate.

However, according to lead researcher Dr. Tzvi Ganel from Ben-Gurion University of the Negev's Department of Psychology, 'plate size doesn't matter as much as we think it does'.

'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.'

Their study, published in the journal Appetite, is the first to examine the way food deprivation affects the perception of food in different contexts.

The new study debunks the popular diet trick based on the Delbouef illusion that predicts people identify portions as larger if they are placed on a smaller plate (stock image)

The new study debunks the popular diet trick based on the Delbouef illusion that predicts people identify portions as larger if they are placed on a smaller plate (stock image)

WHAT IS THE DELBOEUF ILLUSION?

The Delboeuf illusion is one type of visual illusion where a dot surrounded by a large ring is typically perceived to be smaller than the same-sized dot surrounded by a small ring.

This optical trick works because your brain perceives the dot in the context of the outer ring.

It was named after the Belgian philosopher and mathematician Joseph Remi Leopold Delboeuf (1831 – 1896), who created it in 1865. 

The Delboeuf illusion is one type of visual illusion where a dot surrounded by a large ring is typically perceived to be smaller than the same-sized dot surrounded by a small ring

The Delboeuf illusion is one type of visual illusion where a dot surrounded by a large ring is typically perceived to be smaller than the same-sized dot surrounded by a small ring

In terms of plate size, the theory goes that having a smaller plate tricks people into thinking they have more food.

However, new research suggests that when people are hungry, they are able to identify food portion accurately, no matter how it is served.

According to the researchers, this indicates that hunger stimulates stronger analytic processing that is not as easily fooled by the illusion.

However, the Delboeuf illusion is widely believed to work in other contexts.

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Researchers found people who hadn't 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 recently enjoyed a slice.

However, this increase in analytical processing only worked when applied to food.

Both groups were similarly inaccurate when asked to compare the size of black circles and wheel covers placed within different sized circles, proving the Delboeuf illusion still works in other contexts. 

According to the researchers, this shows that hunger stimulates stronger analytic processing and is not as easily fooled by the illusion.

'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,' said Dr. 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.'

 

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