Validity of the Remote Food Photography Method (RFPM) for estimating energy and nutrient intake in near real-time

Abstract

Two studies are reported; a pilot study to demonstrate feasibility followed by a larger validity study. Study 1's objective was to test the effect of two ecological momentary assessment (EMA) approaches that varied in intensity on the validity/accuracy of estimating energy intake (EI) with the Remote Food Photography Method (RFPM) over 6 days in free-living conditions. When using the RFPM, Smartphones are used to capture images of food selection and plate waste and to send the images to a server for food intake estimation. Consistent with EMA, prompts are sent to the Smartphones reminding participants to capture food images. During Study 1, EI estimated with the RFPM and the gold standard, doubly labeled water (DLW), were compared. Participants were assigned to receive Standard EMA Prompts (n = 24) or Customized Prompts (n = 16) (the latter received more reminders delivered at personalized meal times). The RFPM differed significantly from DLW at estimating EI when Standard (mean ± s.d. = -895 ± 770 kcal/day, P < 0.0001), but not Customized Prompts (-270 ± 748 kcal/day, P = 0.22) were used. Error (EI from the RFPM minus that from DLW) was significantly smaller with Customized vs. Standard Prompts. The objectives of Study 2 included testing the RFPM's ability to accurately estimate EI in free-living adults (N = 50) over 6 days, and energy and nutrient intake in laboratory-based meals. The RFPM did not differ significantly from DLW at estimating free-living EI (-152 ± 694 kcal/day, P = 0.16). During laboratory-based meals, estimating energy and macronutrient intake with the RFPM did not differ significantly compared to directly weighed intake.

Conflict of interest statement

Disclosure

The authors have no conflicts of interest to disclose

Figures

Figure 1

When using the RFPM, participants use a Smartphone to capture images of their food selection, plate waste, and a reference card. These images are then immediately sent to a server for analysis.

Figure 2

The RFPM uses EMA methods to improve data quality and minimize missing data. Prompts are automatically sent to participants’ Smartphones to remind them to capture images of their foods and to send these images to the research staff (the images are received by, and managed in, a computer program called the Food Photography Application©). The Food Photography Application© also stores responses to the prompts, and it sends automated reports to the research team and they can quickly identify when data acquisition problems occur.

Figure 3

Bland and Altman analysis comparing energy intake (EI) estimated with the Remote Food Photography Method (RFPM) to the gold standard - EI measured with doubly labeled water (DLW). The RFPM’s error was similar across levels of EI in the Standard Prompt (Panel A) and Customized Prompt (Panel B) groups from Study 1, as well as the sample from Study 2 (Panel C).