Struggling to lose weight? Blame it on Delboeuf.

Amongst the planet’s most popular games, the blame game is a strong contender for the number on spot; specially for those struggling to keep off weight. You’re welcome to direct some ire at Joseph Delboeuf, a 19th-century Belgian philosopher. But why?

Delboeuf discovered that people perceive two identical circles differently when surrounded by concentric circles of different sizes. The effect, now called the Delboeuf illusion, is best explained by the diagram below, wherein the purple circle on the left, looks smaller than that on the right:

The reality is, plate size secretly influences how much food we eat. A 2012 study conducted by Cornell marketing scholar Wansink showed that the illusory effect carries over to our dishes and portion sizes. Imagine the purple circles with rice and the white ones being the actual dish, the dish on the left would look like it had less food than the dish on the right.

Plate sizes guide our intake

What this proves is simply: the way our dishes are designed, subliminally influence the food portions we consume. In the above example, most of us would unconsciously add some rice to the larger dish on the left and remove some rice from the small dish on the right. Anything else wouldn’t ‘look right’. This adjustment would end up in the person with the small dish eating less food, for purely illusory reasons.

What’s now clear is, we base our portions on plate size, rather than hunger. A recently published study by the Journal of Experimental Psychology, revealed that average people prefer a plate or bowl that’s about 70% full; irrespective of the size of the dish used. This implies that by using smaller dishes, we eating a lot less food over time.

The analytical thinkers amongst us may argue that people who serve themselves smaller portions on smaller dishes will simply take seconds because they’ll still be hungry. That could be a reality in places. The point however is, we don’t base our portions on hunger, we base it on plate size. Some people could well be ok with 70% of a small dish, while for others it wouldn’t be.

This discovery now partially explains why people take larger portions even when they know they shouldn’t. But this perception weakness can easily be turned into a strength, simply by changing our food environment, viz. changing our plate size. A point borne true by a 4-month experiment on over 200 households in the USA. It was reported that people randomly assigned to use smaller dishes lost three pounds more than those given larger dishes.

A practical application of the portion principle, is the Portion Plate. This plate helps regulate the portions of food its users take, and also reminds them of what they should fill their plate with.