Division for Risk Assessment and Nutrition, The National Food Institute, Technical University of Denmark, Søborg, Denmark.
J Hum Nutr Diet. 2018 Feb;31(1):131-140. doi: 10.1111/jhn.12490. Epub 2017 Jun 27.
Visual aids, such as food photographs, are widely used in estimating food quantities in dietary surveys. The present study aimed to assess how accurately Danish adults and children can estimate food portion sizes using 37 series of photographs illustrating four to six different portion sizes under real-life conditions; determine whether adults were more accurate than children; and estimate the error caused by using portion size photographs to estimate weights of foods consumed in macronutrient calculation.
Six hundred and twenty-two adults and 109 children were recruited in three workplace canteens and in two schools, respectively, to estimate their lunchtime portions based on photographs. Participants were instructed to keep the foods separated on their plate when taking lunch. Participants thereafter estimated their own portions by looking at the relevant series of photographs. The actual food portions were then weighed.
The proportion of correct estimations was 42% overall (range 19-77%). The mean difference (%) between estimated and actual weight was 17% (range 1-111%). Small portion size photographs were more often used correctly compared to larger portion photographs. Children had as many correct estimations as adults, although they overestimated portions more. Participants using fractions of (or more than) one photograph to estimate the portion of a food had significantly larger errors. When calculating the macronutrient content of a weekly menu using the estimated portion sizes, protein had the largest error (29%).
When used in a real-life situation, the portion size photographs validated in the present study showed a certain inaccuracy compared to the actual weights.
在膳食调查中，视觉辅助工具（如食物照片）被广泛用于估计食物量。本研究旨在评估丹麦成年人和儿童在实际条件下使用 37 组照片（显示四个至六个不同的份量）准确估计食物份量的能力；确定成年人是否比儿童更准确；并估计使用份量照片估计宏量营养素计算中所消耗食物重量时产生的误差。
分别在三个工作场所食堂和两所学校招募了 622 名成年人和 109 名儿童，要求他们根据照片估计午餐时的份量。参与者被指示在用餐时将食物分开。之后，参与者通过查看相关系列照片来估计自己的份量。然后实际称重食物份量。
总体而言，正确估计的比例为 42%（范围为 19-77%）。估计重量与实际重量之间的平均差异（%）为 17%（范围为 1-111%）。与较大份量的照片相比，较小份量的照片更常被正确使用。尽管儿童的估计份量过高，但他们与成年人一样有相同数量的正确估计。参与者使用（或超过）一张照片的分数来估计食物份量，其误差显著更大。当使用估计的份量来计算每周菜单的宏量营养素含量时，蛋白质的误差最大（29%）。
当在实际生活情况下使用时，与实际重量相比，本研究中验证的份量照片显示出一定的不准确性。
