Location: Children's Nutrition Research CenterTitle: Assessment of the accuracy of portion size reports using computer-based food photographs aids in the development of an automated self-administered 24-hour recall ) Author
Submitted to: Journal Of The American Dietetic Association
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/22/2009
Publication Date: 1/1/2010
Citation: Subar, A.F., Crafts, J., Zimmerman, T.P., Wilson, M., Mittl, B., Islam, N.G., McNutt, S., Potischman, N., Buday, R., Hull, S.G., Baranowski, T., Guenther, P.M., Willis, G., Tapia, R., Thompson, F.E. 2010. Assessment of the accuracy of portion size reports using computer-based food photographs aids in the development of an automated self-administered 24-hour recall. Journal of the American Dietetic Association. 110(1):55-64. Interpretive Summary: On of the big problems is self reporting of dietary intake is having people accurately report how much they ate. Having people identify how much they had by selecting from among pictures of foods in successively larger portion sizes offers promise of improving accuracy of portion estimation. Many questions exist about how those pictures should be presented and whether they enhance accuracy. Two studies revealed that accuracy was not improved by having top down pictures of the foods (90° angle), 45° angle pictures (which should give better three dimensionality), images of mounds of foods, or using pictures of household measures. Greater accuracy was obtained with 8 pictures rather than 4. And participants greatly preferred having 8 pictures on the screen at once versus scrolling through single pictures at a time. As a result a computerized 24-hour dietary recall for use by adults will use 8 top down pictures all on the screen at the same time.
Technical Abstract: The objective of the study is to assess the accuracy of portion-size estimates and participant preferences using various presentations of digital images. Two observational feeding studies were conducted. In both, each participant selected and consumed foods for breakfast and lunch, buffet style, serving themselves portions of nine foods representing five forms (eg, amorphous, pieces). Serving containers were weighed unobtrusively before and after selection as was plate waste. The next day, participants used a computer software program to select photographs representing portion sizes of foods consumed the previous day. Preference information was also collected. In Study 1 (n=29), participants were presented with four different types of images (aerial photographs, angled photographs, images of mounds, and household measures) and two types of screen presentations (simultaneous images vs an empty plate that filled with images of food portions when clicked). In Study 2 (n=20), images were presented in two ways that varied by size (large vs small) and number (4 vs 8). We used repeate-measures analysis of variance of absolute differences between actual and reported portions sizes by presentation methods. Accuracy results were largely not statistically significant, indicating that no one image type was most accurate. Accuracy results indicated the use of eight vs four images was more accurate. Strong participant preferences supported presenting simultaneous vs sequential images. These findings support the use of aerial photographs in the automated self-administered 24-hour recall. For some food forms, images of mounds or household measures are as accurate as images of food and, therefore, are a cost-effective alternative to photographs of foods.