July 10, 2012 -- Call it the cut-up-food-diet: We feel full faster, and eat less later, when our food is served in small pieces.
It works in both college students and lab rats, according to a study by Devina Wadhera and colleagues at Arizona State University.
"Cutting up energy-dense foods into smaller pieces may be beneficial to dieters who wish to make their meal more satiating while also maintaining portion control," Wadhera says in a news release.
The researchers first tried this on lab rats. The animals were trained to run through a maze. Then the animals were offered a reward for running quickly through the maze. For 20 rats, the reward was a single chunk of food. For another 20 rats, the reward was 30 small pieces of food weighing the same as the large piece offered to the other rats.
After 12 trips through the maze, the result was clear. Rats preferred -- and worked harder for -- the same amount of food served in smaller pieces.
Okay, it's easy to fool a rat. But what about college students?
Wadhera's team split 301 male and female students into two groups. One was offered a whole bagel covered with cream cheese. The other group was offered the same kind of bagel, cut into four pieces and covered with the same amount of cream cheese.
The group that got the whole bagel ate a little more of it than those who got the cut-up bagel. But the real difference came 20 minutes later, when all of the students were offered a free meal.
Those who'd eaten the cut-up bagel -- even though they'd eaten a little less -- ate less of the free meal.
"Perhaps cutting up foods into multiple, bite-sized pieces may perceptually look like more and therefore elicit greater satiation than a single-piece food portion," Wadhera and colleagues suggest.
The study was presented at the annual meeting of the Society for the Study of Ingestive Behavior, held this week in Zurich, Switzerland.
These findings were presented at a medical conference. They should be considered preliminary as they have not yet undergone the "peer review" process, in which outside experts scrutinize the data prior to publication in a medical journal.