Food Photography Is Not an Accurate Measure of Energy Intake in Obese, Pregnant Women

Abstract

Background: To improve weight management in pregnant women, there is a need to deliver specific, data-based recommendations on energy intake.

Objective: This cross-sectional study evaluated the accuracy of an electronic reporting method to measure daily energy intake in pregnant women compared with total daily energy expenditure (TDEE).

Methods: Twenty-three obese [mean ± SEM body mass index (kg/m2): 36.9 ± 1.3] pregnant women (aged 28.3 ±1.1 y) used a smartphone application to capture images of their food selection and plate waste in free-living conditions for ≥6 d in early (13-16 wk) and late (35-37 wk) pregnancy. Energy intake was evaluated by the smartphone application SmartIntake and compared with simultaneous assessment of TDEE obtained by doubly labeled water. Accuracy was defined as reported energy intake compared with TDEE (percentage of TDEE). Ecological momentary assessment prompts were used to enhance data reporting. Two-one-sided t tests for the 2 methods were used to assess equivalency, which was considered significant when accuracy was >80%.

Results: Energy intake reported by the SmartIntake application was 63.4% ± 2.3% of TDEE measured by doubly labeled water (P = 1.00). Energy intake reported as snacks accounted for 17% ± 2% of reported energy intake. Participants who used their own phones compared with participants who used borrowed phones captured more images (P = 0.04) and had higher accuracy (73% ± 3% compared with 60% ± 3% of TDEE; P = 0.01). Reported energy intake as snacks was significantly associated with the accuracy of SmartIntake (P = 0.03). To improve data quality, excluding erroneous days of likely underreporting (<60% TDEE) improved the accuracy of SmartIntake, yet this was not equivalent to TDEE (-22% ± 1% of TDEE; P = 1.00).

Conclusions: Energy intake in obese, pregnant women obtained with the use of an electronic reporting method (SmartIntake) does not accurately estimate energy intake compared with doubly labeled water. However, accuracy improves by applying criteria to eliminate erroneous data. Further evaluation of electronic reporting in this population is needed to improve compliance, specifically for reporting frequent intake of small meals. This trial was registered at www.clinicaltrials.gov as NCT01954342.

Figures

FIGURE 1

Daily TDEE and reported EI in obese, pregnant women; n = 23. The number of observation periods with EI (n = 45) and energy expenditure (n = 45), respectively, are presented as histograms by using bins of 200 kcal/d. EI, energy intake; TDEE, total daily energy expenditure.

FIGURE 2

Comparison between TDEE and reported EI in obese, pregnant women; n = 23. Values are means compared with the differences between reported EI and TDEE for each assessment period. The measures of accuracy for obesity classes are presented as means ± SEMs (class I, n = 10; class II, n = 7; class III, n = 6). (A) Raw SmartIntake data; (B) only days with >60% TDEE; (C) only days with >1000 kcal/d; (D) only days with >1 meal/d. EI, energy intake; TDEE, total daily energy expenditure.

FIGURE 3

Snacking and the accuracy of SmartIntake. Values are presented as EI reported as snacks (Snacking; percentage of reported EI) compared with the accuracy of reported EI compared with TDEE (percentage of TDEE) for each assessment period. (A) Raw SmartIntake data; (B) only days with >60% TDEE included in analyses. EI, energy intake; TDEE, total daily energy expenditure.