August 4, 2006

Device helps judge size of wedge-shaped foods

NEW YORK -- For people watching how much they eat, it can be difficult to estimate the portion sizes of wedge-shaped foods like pizza, cake and pie. A handy new tool may help, a study shows.

Dr. Sandria Goodwin of Tennessee State University in Nashville and colleagues developed an adjustable wedge to help gauge portion size of triangular foods. They then compared the accuracy of the wedge against a ruler, having 320 people use both tools to estimate the portion size of a variety of foods, including three different-sized slices each of pie, cake and pizza.

Participants viewed each portion for 30 seconds, after which it was removed. They were then asked to estimate its size using the adjustable wedge and then the ruler, and were also asked how confident they were in the accuracy of their estimate.

Even using the tools, the researchers found, people frequently made inaccurate estimations of portion size. People tended to underestimate the size of "lower profile" foods like pizza and pie, while they overestimated the size of thicker foods such as cake. In one-third of cases, the wedge was more accurate than the ruler.

People were more confident in their estimates with the adjustable wedge -- even though these measurements were not necessarily more accurate -- and said they preferred it to the ruler.

"Because subjects were less intimidated when using the adjustable wedge, ruler-challenged clients may find the adjustable wedge a helpful tool," the researchers conclude.

SOURCE: Journal of the American Dietetic Association, August 2006.