Development and Validation of a Photographic Method to Use for Dietary Assessment in School Settings

ObjectiveTo develop and validate a photographic method aimed at making assessment of dietary intake in school canteens non-obstrusive, practical and feasible.MethodsThe study was conducted in two elementary schools representing two different school canteen systems; main dish being served by canteen staff (Iceland), and complete self-serving (Sweden). Food items in serving and leftovers were weighed and photographed. Trained researchers estimated weights of food items by viewing the photographs and comparing them with pictures of half and full reference portions with known weights. Plates of servings and leftovers from 48 children during five school days (n = 448 plates) and a total of 5967 food items were estimated. The researchers’ estimates were then compared with the true weight of the foods and the energy content calculated.ResultsWeighed and estimated amounts correlated across meals both in grams and as total energy (0.853–0.977, pConclusionsThe photographic method provides acceptable estimates of food and energy intake in school canteens. However, greater accuracy can be expected when foods are served by canteen staff compared with self-serving.