Evaluation of a digital method to assess evening meal intake in a free-living adult population

BACKGROUND In recent years new applications of technologies, including digital images, to capture dietary behaviour in real time have been explored. OBJECTIVES To validate a digital method for estimating evening meal intake in a free-living adult population, and to examine the feasibility of the method for recording evening meal intake over a prolonged period of time. DESIGN The digital method was compared against weighed records of 19 participants' usual evening meals for five consecutive days. Two trained image analysts independently estimated the weight of individual foods within the meals into major food categories, and the nutrient content was calculated. A second study included interviews with 28 participants recording their evening meals on weekdays for three consecutive weeks to get their perspective on the feasibility of the method. RESULTS High correlation coefficients between the digital method and weighed records were found for all measured food categories and nutrients. Comparable means and acceptable limits of agreement (mean difference +/- 2 SD) were found with regard to macronutrient distribution (e.g. fat content -5 to 6 E%), energy density (-75 to 91 kJ/100 g), and energy-adjusted foods (e.g. fruit and vegetable content -241 to 236 g/10 MJ). The majority of the participants expressed satisfaction with the method and were willing to record their evening meals for 1 month or more using the digital method. CONCLUSION The digital method is valid and feasible for evening meal estimation in real-time where a prolonged recording period of participants' meals is needed.