Cutting up food into smaller pieces may help people control their weight more easily because they are more satisfying to eat than one large piece with the same number of calories, according to a new study presented at a conference this week.

The 2012 meeting of the Society for the Study of Ingestive Behavior, which runs from 10 to 14 July in Zurich, Switzerland, heard how the researchers concluded that humans, like animals, seem to find eating food as smaller pieces more enjoyable and satisfying.

In a press release issued on Tuesday, lead author Devina Wadhera, from the Department of Psychology at Arizona State University in the US, suggests:

"Cutting up energy-dense meal foods into smaller pieces may be beneficial to dieters who wish to make their meal more satiating while also maintaining portion control."

Previous studies have already suggested that larger portions lead people to eat more. For this study, Wadhera and colleagues focused on the number and size of food pieces, because it is also known that humans and other animals judge food quantity using several cues, of which number is one, with larger numbers usually taken to mean larger amounts.

For instance, in 1989, a team of researchers ran a series of intriguing experiments with rats in mazes. In the first experiment they trained rats in a T-maze using 4 x 75 mg food pellets in one arm of the T, and a single 300 mg pellet in the other arm.

The rats developed a preference for the 4 x 75 mg arm, and when the researchers reversed the arms, the rats also switched their preference. This indicated, when faced with the same weight of food, the rats preferred the four-pellet alternative to the single pellet one.

In a slightly different version of the experiment, the researchers put 4 x 45 mg pellets in one arm and a single 300 mg pellet in the other. But this time the rats showed a preference for the 300 mg arm, indicating they were choosing weight over number of pieces. This was confirmed in a third experiment, when the choice was either 4 x 45 mg, or 4 x 75 mg pellets.

The researchers in that study concluded that rats prefer multiple to single food units, and judge a given weight of food as greater when the number of units is greater. They proposed that this apparent "failure of conservation" may be common to other species, including humans.

So to test the idea in humans, Wadhera and colleagues invited 301 college students to take part in an experiment where they gave each an 82 g bagel, either uncut or cut into four.

Twenty minutes after eating the bagel, the students were invited to eat as much as they wanted from a measured amount of food at a free lunch (the test meal).

Any left over bagel or test meal was then measured to assess what each student had eaten.

The results showed that the students who ate the single, uncut bagel, ate more calories from both the bagel and the test meal, than their fellow counterparts who were given the bagel as four pieces.

Wadhera said this showed that eating food cut into several pieces may be more satiating than eating it as a single, uncut portion.

The idea of manipulating perception to fool the body about food, was also taken up in another study reported in February 2012, where researchers from the Netherlands found that manipulating the aroma of food caused people to take smaller bites, resulting in up to 10% reduction in intake per bite. They suggested aroma control combined with portion control could fool the body into thinking it was full with a smaller amount of food.

Written by Catharine Paddock PhD