Estimating Portion Sizes of Wedge-Shaped Foods

09/08/06 Accurately estimating portion sizes is essential in patient counseling and nutrition research, and registered dietitians often use "estimation aids" like rulers to assist their clients in determining how much they are eating. But many foods that are high in sugar, calories and saturated fats - such as cake, pie and pizza - often are served in wedge-shaped pieces, which studies have shown can make it difficult for people to estimate portions.

Researchers at Tennessee State University have developed an adjustable wedge and compared people's ability to estimate portion sizes using it and a ruler. The wedge was tested with 320 adults using different sizes and types of wedge-shaped foods. The findings show the adjustable wedge estimation aid does appear to reduce the average estimation error for some larger portions of wedge-shaped foods.

The researchers write that "substantial misestimation" by people using the adjustable wedge means "regardless of aid, some people have difficulty estimating portions of wedge-shaped foods." Still, they add: "The adjustable wedge was easy for people to use and can be recommended as an option for estimating portion size of wedge-shaped foods."