Performance of the Digital Dietary Assessment Tool MyFoodRepo

Abstract

Digital dietary assessment devices could help overcome the limitations of traditional tools to assess dietary intake in clinical and/or epidemiological studies. We evaluated the accuracy of the automated dietary app MyFoodRepo (MFR) against controlled reference values from weighted food diaries (WFD). MFR's capability to identify, classify and analyze the content of 189 different records was assessed using Cohen and uniform kappa coefficients and linear regressions. MFR identified 98.0% ± 1.5 of all edible components and was not affected by increasing numbers of ingredients. Linear regression analysis showed wide limits of agreement between MFR and WFD methods to estimate energy, carbohydrates, fat, proteins, fiber and alcohol contents of all records and a constant overestimation of proteins, likely reflecting the overestimation of portion sizes for meat, fish and seafood. The MFR mean portion size error was 9.2% ± 48.1 with individual errors ranging between -88.5% and +242.5% compared to true values. Beverages were impacted by the app's difficulty in correctly identifying the nature of liquids (41.9% ± 17.7 of composed beverages correctly classified). Fair estimations of portion size by MFR, along with its strong segmentation and classification capabilities, resulted in a generally good agreement between MFR and WFD which would be suited for the identification of dietary patterns, eating habits and regime types.

Keywords: accuracy; app; diet; dietary assessment; food intake; mobile food record; validation.

Figure 1

Mean weight errors per food group (NaNs: non-alcoholic non-sweetened; NaS: Non-alcoholic sweetened). Boxplots give median, interquartile range (IQR) and maximum 1.5 IQR. Colored boxplots indicate significant mean differences between estimated and true values (two-sided p-value ≤ 0.05). Four weight transcription errors resulting from unrealistic entries in the food diaries were removed from portion size analysis (not shown). * Only one observation in the “milk substitutes” food group.

Figure 2

Overall performance for energy and macronutrient content: Linear regression of MFR versus controlled values for all found records, for content of (a) energy; (b) fat; (c) carbohydrates; (d) protein; (e) fiber and (f) alcohol. (Black line: linear regression line; dotted line: 95% limits of agreement; grey line: y = x).