Relevance of the Findings
In contrast with 2 recent systematic reviews and meta-analyses that pooled findings from eHealth interventions targeting children and adolescents [When we corrected for app use in our RCT analyses, our findings related to the efficacy of the app did not change, suggesting that the total number of minutes spent in the app over 3 months did not predict changes in health behaviors over time. However, it is worth noting that a crude measure of engagement (total time spent in the app) might not provide a nuanced and comprehensive picture of what aspects of the intervention “works” or leads to changes in health outcomes. Factor mixture modeling of web-analytics data from a previous version of the app among 301 teens who used the app for 4.5 months revealed distinct engagement profiles ranging from “uninvolved” teens to “dabblers,” “engaged,” and finally “keeners” [Our findings suggest that the Aim2Be app might have had some effects on the waitlisted control participants. Although initially challenging to understand, there may be some plausible explanations for these findings. There could be seasonality effects, as the randomization of participants for this RCT could not be spread over the course of a full year. It is also possible that participants randomized to the waitlist intervention arm (control participants), who remained in the study to receive the intervention from 3 to 6 months, had greater motivation or readiness for change compared with participants randomized to the intervention arm. In a separate exploratory analyses, we found that adolescents in the waitlisted control group reported decreased total daily calories and energy from solid fats (saturated fats and trans fats) during the waitlist period (0-3 months; Our findings suggest that providing participants with access to a web-based live coach did not enhance the intervention. It is worth highlighting that relatively few participants engaged with the live coach via SMS text messaging and even fewer participants set up web-based appointments. Although approximately half of the individuals randomized to the app with live coach conditions sent at least one chat message to the live coach, none of the parents set an internet-based face-to-face appointment, making it difficult to assess whether the support of the live coach yielded additional benefits overall. Although intervention participants exposed to the app with a live coach experienced improvement in self-reported (but not objectively measured) PA compared with waitlisted intervention participants, these differences could be attributed to seasonality effects, as the randomization of participants for this RCT could not be spread over the course of a full year.Previous research has shown the key role of parents in supporting health behavior changes through the household environment [