Measuring lunchtime consumption in school cafeterias: a validation study of the use of digital photography

Abstract

ObjectiveThe present study tested the validity of a digital image-capture measure of food consumption suitable for use in busy school cafeterias.DesignLunches were photographed pre- and post-consumption, and food items were weighed pre- and post-consumption for comparison.SettingA small research team recorded children’s lunchtime consumption in one primary and one secondary school over seven working days.ParticipantsA primary-school sample of 121 children from North Wales and a secondary-school sample of 124 children from the West Midlands, UK, were utilised. Nineteen children were excluded because of incomplete data, leaving a final sample of 239 participants.ResultsResults indicated that (i) consumption estimates based on images were accurate, yielding only small differences between the weight- and image-based judgements (median bias=0·15–1·64 g, equating to 0·45–3·42 % of consumed weight) and (ii) good levels of inter-rater agreement were achieved, ranging from moderate to near perfect (Cohen’sκ=0·535–0·819). This confirmed that consumption estimates derived from digital images were accurate and could be used in lieu of objective weighed measures.ConclusionsOur protocol minimised disruption to daily lunchtime routine, kept the attrition low, and enabled better agreement between measures and raters than was the case in the existing literature. Accurate measurements are a necessary tool for all those engaged in nutrition research, intervention evaluation, prevention and public health work. We conclude that our simple and practical method of assessment could be used with children across a range of settings, ages and lunch types.

Evaluation of a Novel WeChat Applet for Image-Based Dietary Assessment among Pregnant Women in China

“…Our results showed that there was less deviation in the estimation of food quantity using the WAIDA method than the recall method, which is the goal we want to achieve. However, similar to previous image-based dietary assessments [ 26 , 27 , 28 ], the amount of food obtained by the WAIDA still showed a disparity with the actual food weight. This may be due to the relative ability of dietary assessors to identify and quantify food in images [ 10 , 19 , 29 ].…”

Changes in the nutritional content of children's lunches after the Food Dudes healthy eating programme

“…In-depth macro- and micronutrient analysis identified that these changes were associated with decreases in fat, saturated fat, and sodium, as well as increases in vitamins C and E. These positive changes were not identified in the control school, suggesting that they can be attributed to the Food Dudes programme rather than seasonal differences in consumption between the two measurement points. These results have significant implications for national-level efforts to reduce the incidence of childhood obesity, and improve childhood nutrition, as recommended by the Department of Health (5) and BMA (1) , and the methodology (27) (and subsequent rich data yielded in the present study) may inform future researchers investigating the health impact of dietary changes in a cafeteria environment.…”

“…Existing research into the effectiveness of the multicomponent healthy eating interventions in primary schools have not used sufficiently sensitive methods to assess macro- and micronutrient changes over time (9,10,12,13) . Using a previously validated digital photography methodology (27) , we were able to estimate food item consumption to a finer-grained scale, to the gram. Further to this, we were also the first to consider the impact on global nutrient consumption at lunchtime, rather than portion size consumption differences alone.…”

“…The digital photography method validated in previous research (27) was used. In the morning, researchers collected lunchboxes: removed, photographed, and replaced their contents.…”

“…In the existing literature, the researchers have typically used food diaries and frequency questionnaires (9,10) to assess consumption to approximate servings, or the more reliable method of direct observation (12,13) to measure differences in fruit and vegetable consumption to the nearest half- or quarter-portion. Though high levels of inter-rater agreement can be achieved (12,13,27) , and measures were more sensitive than standard dietary recall estimates in recording small but significant improvements (11) , no previous assessment of a multicomponent intervention has been able to consider changes to children's consumption at a more detailed level of macro- and micronutrients, or indeed investigate dietary change to the level of individual children. Instead, results were reported by cohort at the ‘portion’ or ‘serving’ level, which are not sufficiently sensitive to assess children's actual nutrient intake and the impact of any displacing influence that participation in multicomponent dietary programs may have on less healthful food consumption.…”