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Research Project: Childhood Obesity Prevention

Location: Children's Nutrition Research Center

Title: Reliability and validity of food portion size estimation from images using manual flexible digital virtual meshes

Author
item Beltran, Alicia - Children'S Nutrition Research Center (CNRC)
item Dadabhoy, Hafza - Children'S Nutrition Research Center (CNRC)
item Ryan, Courtney - Children'S Nutrition Research Center (CNRC)
item Dholakia, Ruchita - Children'S Nutrition Research Center (CNRC)
item Baranowski, Janice - Children'S Nutrition Research Center (CNRC)
item Li, Yuecheng - University Of Pittsburgh
item Yan, Guifang - University Of Pittsburgh
item Jia, Wenyan - University Of Pittsburgh
item Sun, Mingui - University Of Pittsburgh
item Baranowski, Tom - Children'S Nutrition Research Center (CNRC)

Submitted to: Public Health Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/21/2017
Publication Date: 2/12/2018
Citation: Beltran, A., Dadabhoy, H., Ryan, C., Dholakia, R., Baranowski, J., Li, Y., Yan, G., Jia, W., Sun, M., Baranowski, T. 2018. Reliability and validity of food portion size estimation from images using manual flexible digital virtual meshes. Public Health Nutrition. http://dx.doi.org/10.1017/S1368980017004293.

Interpretive Summary: To overcome problems in self-report of diet, attempts are being made to analyze all day images for dietary intake. To assess portion size/amount consumed in an image, wire mesh software was developed to superimpose on a two dimensional image to obtain a three dimensional assessment of volume. This manuscript compared the intercoder reliability in using the wire mesh procedure between 2 dietitians with experience in using the wire mesh and 3 engineers who helped create it, and assessed their agreement with a true known value. The engineers did better than the dietitians on all tests of reliability and validity. This indicates that even experienced dietitians would benefit from training in optional use of the wire mesh procedure.

Technical Abstract: The eButton takes frontal images at 4 second intervals throughout the day. A three-dimensional (3D) manually administered wire mesh procedure has been developed to quantify portion sizes from the two-dimensional (2D) images. This paper reports a test of the interrater reliability and validity of use of the wire mesh procedure. Seventeen foods of diverse shapes and sizes served on plates, bowls and cups were selected to rigorously test the portion assessment procedure. A dietitian not involved in interrater reliability assessment used standard cups to independently measure the quantities of food to generate the "true" value for a total of 75 "served" and 75 smaller "left" images with diverse portion sizes. The images appeared on the computer to which the digital wire meshes were applied. Two dietitians and three engineers independently estimated portion size of the larger ("served") and smaller ("left") images for the same foods. The engineers had higher reliability and validity than the dietitians. The dietitians had lower reliabilities and validities for the smaller more irregular images, but the engineers did not, suggesting training could overcome this limitation. The lower reliabilities and validities for foods served in bowls, compared to plates, suggest difficulties with the curved nature of the bowls. The wire mesh procedure is an important step forward in quantifying portion size which has been subject to substantial self report error. Improved training procedures are needed to overcome the identified problems.