Obesity alert study: Portion size labels can be deliberately confusing and consumers are easily, even willingly, fooled

Yikes! According to the Centers for Disease Control and Prevention, the "large" soda you order today is about six times as large as the one you ordered 60 years ago. "Food sizes have become larger over time," says Aradhna Krishna, a University of Michigan marketing professor who has been looking into portion size and perception. "So, that same hamburger has become bigger, the french fries have become bigger, and again this is leading to obesity."

Thinking a lot about this, Krishna tried an experiment. She gave people cookies that were labeled either medium or large, and then measured how much they ate. "The catch? The cookies were identical in size, What happened? You guessed it," reports NPR's Helen Thompson and Shanikar Vedantam. "People ate more cookies when they were labeled 'medium.' Rather than trust what their stomachs were telling them, in other words, people went by the label." It gets worse: "(They) think they've not eaten as much," says Krishna.

The researcher said women have known all about this principle for awhile, because it's what's been happening with sizes of clothing. It's something called "vanity sizing."  "What used to be a size 8 in the 1950s has become a size 4 in the 1970s and a zero in 2006," Krishna said. It makes you feel better about yourself and your body image. The real question, she asks, is how much do we want to be lied to or, indeed, how much do we lie to ourselves? (Read more)