Study: Surroundings Play Key Role in Diet

Wendy's International founder Dave Thomas, is shown in this 1994 photo holding a tray carrying a sandwich, a large-sized drink and a copy of his autobiography. A study offers new evidence that people take cues from their surroundings in deciding how much to eat. It explains why, for example, people who used to be satisfied by a 12-ounce can of soda may now feel that a 20-ounce bottle is just right. (AP Photo/Chris Kasson) (Chris Kasson - AP)

Brian Wansink, director of Cornell University's Food and Brand Lab and author of the forthcoming book "Mindless Eating: Why We Eat More Than We Think," called the new paper an impressive demonstration of the effect in a real-world setting. He has done similar work but didn't participate in Geier's research.

So can all this help dieters?

Some food companies are introducing products in 100-calorie packages, and Geier thinks that could help hold down a person's consumption. He also suspects companies could help by displaying the number of servings per container more prominently on their packaging.

As for what dieters can do on their own, Geier said one of his overweight patients offered a suggestion for restaurant visits: Request that the meal be split in two in the kitchen, with half on the plate and the other half packaged to take home.

In any case, an earlier experiment of Geier's shows that the unit bias effect has its limits.

He had one dining hall at his university provide 10-ounce glasses for soda, and a second provide 16-ounce glasses. He predicted that students at the first hall would drink less soda. In fact, they drank more.

Only later did he find out what went wrong.

"They were taking two glasses at a time," he said. "I guess I went below what is culturally construed as a unit of soda."