Public Health Nutrition

Research Article

Accuracy of estimates of food portion size using food photographs – the importance of using age-appropriate tools

Emma Fostera1 c1, John NS Matthewsa2, Michael Nelsona3, Julie M Harrisa4, John C Mathersa1 and Ashley J Adamsona1

a1 Human Nutrition Research Centre, University of Newcastle upon Tyne, William Leech Building, Medical School, Framlington Place, Newcastle upon Tyne NE2 4HH, UK

a2 School of Mathematics and Statistics, University of Newcastle upon Tyne, Newcastle upon Tyne, UK

a3 Department of Nutrition and Dietetics, King's College London, London, UK

a4 School of Psychology, University of St Andrews, St Andrews, UK

Abstract

Background In order to obtain a measure of nutrient intake, a measure or estimate of the amount of food consumed is required. Weighing foods imposes a large burden on subjects, often resulting in underreporting. Tools are available to assist subjects in providing an estimate of portion size and these include food photographs. The application of these tools in improving portion size estimation by children has not been investigated systematically.

Objectives To assess the accuracy with which children are able to estimate food portion sizes using food photographs designed for use with adults, and to determine whether the accuracy of estimates is improved when age-appropriate portion size photographs are provided.

Design Original data from three separate studies, on the accuracy of portion size estimates by adults using food photographs, by children using adult photographs and by children using age-appropriate photographs, are analysed and compared.

Subjects One hundred and thirty-five adults aged 18 to 90 years and 210 children aged 4 to 11 years.

Results Children's estimates of portion sizes using age-appropriate food photographs were significantly more accurate (an underestimate of 1% on average) than estimates using photographs designed for use with adults (an overestimate of 45% on average). Accuracy of children's estimates of portion size using age-appropriate photographs was not significantly different from that of adults. Children overestimated a food's weight by 18% on average and adults underestimated by 5%.

Conclusions Providing children with food photographs depicting age-appropriate portion sizes greatly increases the accuracy of portion size estimates compared with estimates using photographs designed for use with adults.

(Received March 14 2005)

(Accepted August 31 2005)

Correspondence

c1 *Corresponding author: Email Emma.Foster@ncl.ac.uk

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