Daily and Seasonal Influences on Dietary Self-monitoring Using a Smartphone Application.

OBJECTIVE: To examine within-person variation in dietary self-monitoring during a 6-month technology-supported weight loss trial as a function of time-varying factors including time in the study, day of the week, and month of the year.

METHODS: Smartphone self-monitoring data were examined from 31 obese adults (aged 18-60 years) who participated in a 6-month technology-supported weight loss program. Multilevel regression modeling was used to examine within-person variation in dietary self-monitoring.

RESULTS: Participants recorded less as time in the study progressed. Fewer foods were reported on the weekends compared with weekdays. More foods were self-monitored in January compared with October; however, a seasonal effect was not observed.

CONCLUSIONS AND IMPLICATIONS: The amount of time in a study and day of the week were associated with dietary self-monitoring but not season. Future studies should examine factors that influence variations in self-monitoring and identify methods to improve technology-supported dietary self-monitoring adherence.