PortionSize Study 3: Assessment in Free-living Conditions

The objective is to test the accuracy of the PortionSize™ app and the MyFitnessPal© app at measuring energy intake in free-living conditions, tested against the gold-standard, doubly labeled water. Participants will use PortionSize™ and MyFitnessPal apps in separate periods to test the accuracy of the respective apps.

We will recruit adults to use the PortionSize app and the MyFitnessPal free-living conditions. In a within subjects and randomized, counterbalanced design, the accuracy of the PortionSize and MyFitnessPal apps at estimating energy intake in free-living conditions will be tested against the gold-standard, doubly labeled water (DLW), over two non-consecutive four-day periods that should include at least one weekend day and encompass the same days of the week during each period. Participants will be trained in our clinic to use the apps prior to their use in free-living conditions. We will integrate customizable notifications and reminders to remotely prompt participants to record data, resolve data collection problems, etc. These notifications and reminders utilize Ecological Momentary Assessment (EMA) methodology to maximize data collection protocol adherence by reminding participants to capture and send food information at relevant times.