Digital photography: A new method for estimating food intake in cafeteria settings

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Abstract
Objective: The primary objective of this study was to test the comparability of digital photography and visual estimation procedures for estimating food intake. Research methods and procedures: The study sample included 71 breakfast meals and 59 lunch meals eaten in a university cafeteria during a single day. A total of 66 different foods were employed as test foods that could be selected by the students. Food selections and plate waste, as estimated by digital photography and visual estimation, were compared. For digital photography, three observers independently estimated portion sizes of each food item based upon digital photographs. One observer estimated portion sizes in the cafeteria setting, using visual estimation, a method that has been validated in other studies. Results: To test the accuracy of the two procedures for measuring food intake, the estimates of food weights derived from both procedures were compared using Bland-Altman regression. In comparison to visual estimation, the digital photography method yielded comparable estimates of food selections, plate waste, and total food intake for seven of nine comparisons. The two methods of estimating food portions yielded comparable results for most (78%) types of foods. The two methods also yielded similar variability. Discussion: These findings suggest that the digital photography method is an alternative to the traditional method of estimating food intake via direct observation.