According to the illusion, if you have two dots of equal size but surround one with a circle, the dot in the circle appears bigger.
So how does this work with food? Ever eat at super fancy restaurant that serves over-priced “small” portions? Well, the portions aren’t small…the plates are just large.
Put a piece of food on a large plate, and your eyes will tell you the portion is too small. Put the same food on a small plate and you think the portion is too large. It’s an optical trick our brains play on us.
So if you use the standard 12″ plate at home, most likely you’re eating more than you realize.
A couple of professors put the Delboeuf Illusion to a test by asking people to re-create a “target” serving size of soups in large and small bowls. Because of the optical illusion, people using the smallest dishes served themselves less food by as much as 12% and overestimated how much food they actually ate.
Likewise, those using the largest dishes served 13% more food than intended and underestimated how much they ate.
Even if folks knew about the optical illusion, the results were the same.
This tells me two things: 1) We are hard-wired that way and it’s difficult to overcome, and 2) Eyeballing it doesn’t work! We completely suck at estimating how much we are eating.
Tools To Outsmart Your Brain
There are a few things you can do to make sure you eat the right portion each time.
- Use Smaller Dishes — The average size of an American dinner plate has increased 23% since 1900! Most dinner plates in the 1950s were 9″ vs. today’s 12″
feedbagplate. I use 9″ paper plates or my 8.5″ salad plates for our meals.
- Use Taller Glasses — Apparently there is also another optical trick our brain plays on us, called T-illusion (very cool test at link). We tend to over pour liquids in short, wide glasses and under pour in tall, thin glasses. Even the best bartenders are not immune (good to know!) from the T-illusion.
- Color Matters — Yep, the color of your plate can cause you to eat more food. Your eyes play a trick on you if your food blends in with the color of your plate: you tend to serve yourself 30% more!
- Measure, Measure and Measure — Our eyes are horrible at estimating portions. I always keep my measuring cups and spoons nearby. But what about when you eat out? There’s a great guide to help you — your hand! Check out Diet To Go’s chart showing portion sizes relative to your hand.
The real key to keeping portion control in check — pay attention to what you are eating.