Dietary Self-Monitoring Through Calorie Tracking but Not Through a Digital Photography App Is Associated with Significant Weight Loss: The 2SMART Pilot Study-A 6-Month Randomized Trial

Abstract

Background: Dietary self-monitoring (DSM) of foods and beverages is associated with weight loss in behavioral interventions; however, DSM may be burdensome, and adherence may decrease over time. Novel methods of DSM, including apps that track food using photographs, may decrease burden, increase DSM adherence, and improve weight loss.

Objective: The objective was to test a mobile photo DSM app compared to a calorie-tracking DSM app on tracking frequency and weight loss in a remotely delivered behavioral weight-loss intervention.

Design: This was a 6-month (October 2016 to April 2017) randomized trial.

Participants/setting: Participants were adults (n=41) classified as overweight or obese (body mass index 25 to 49.9) from South Carolina.

Intervention: Participants received remotely delivered twice-weekly behavioral weight-loss podcasts and tracked diet using a calorie-tracking DSM app (Calorie Group) or a photo DSM app (Photo Group).

Main outcome measures: Main outcomes were the number of days diet was tracked, podcasts downloaded, and weight change at 6 weeks and 6 months.

Statistical analyses: Researchers used nonparametric Wilcoxon rank sum tests and χ² analysis to test for differences between groups at baseline; repeated-measures models to estimate weight change and Spearman correlations to determine relationships between DSM frequency, podcasts downloaded, and weight change at 6 months.

Results: There were no differences between groups for the number of days that diet was recorded (P=0.18), which was low overall (<30% of days) but was statistically significantly and strongly correlated with weight change for all participants pooled (r=0.63; P<0.001) and for the calorie tracking group (r=0.70; P=0.004), but not the photo tracking group (r=0.51; P=0.06). Participants in both groups had significant weight loss at 6 months (Photo Group, -2.5±0.9 kg; P=0.008; Calorie Group -2.4±0.9 kg; P=0.007), with no differences between groups at either 6 weeks (P=0.66) or at 6 months (P=0.74).

Conclusions: As part of a remotely delivered weight loss intervention, frequency of DSM was significantly associated with overall weight loss for participants using a calorie DSM app but not a photo DSM app. DSM was low regardless of group and weight loss was significant, although minimal. Increasing user engagement with any DSM may be important to increase self-monitoring and improve weight loss.

Trial registration: ClinicalTrials.gov NCT02868853.

Keywords: Dietary self-monitoring; Mobile health; Obesity; Photograph; Weight loss.