Inclusion Criteria:

1. 14-21 years old
2. Has an iPhone or are willing to use a study iPhone
3. Ability to read and speak English
4. Endorsement of one of the three items listed below on the five-item S-weight questionnaire indicating motivation for change During the last year I haven't done anything to lose weight but I'm planning to do something over the next 30 days.

I've been making an effort to lose weight (by dieting1 and/or exercising2) for less than 6 months.

I've been making an effort to maintain my weight (by dieting1 and/or exercising2) for more than 6 months.

6. Body mass index [BMI] ≥85th percentile for age and gender

Exclusion Criteria:

1. Any psychiatric condition and/or developmental delay which would require immediate or ongoing treatment that would make study participation difficult or harmful
2. Parent/guardian-reported physical, mental of other inability to provide consent or refusal to provide consent for minor children
3. Self-reported diagnosis of Prader-Willi Syndrome, brain tumor, hypothalamic obesity, or other diagnosis associated with obesity
4. Concurrent participation in an alternative weight loss intervention
5. Participation in the study team's previous app weight loss studies (exclusion for trial but not beta testing participants)