This study examines the results of two remotely delivered weight loss interventions administered. The first study, the Pounds Off Digitally (POD) Study, was a 3-month randomized controlled weight loss trial among overweight adults, which compared an existing popular weight loss podcast on iTunes to an enhanced, theory-based podcast designed by the researchers. The podcasts used in POD and mPOD have been described elsewhere. Briefly, podcasts were designed using constructs from Social Cognitive Theory and were, on average, 15 minutes in length. Podcasts contained a section on nutrition and physical activity information, an audio blog of a man or a woman trying to lose weight, a soap opera, and a goal setting activity. The second study, the mobile Pounds Off Digitally study, was a 6-month randomized weight loss trial among overweight adults, which compared the TBP to the TBP plus self-monitoring of diet and PA using a mobile app and social support delivered via the social network Twitter.
In POD, participants were required to own an MP3 player to enroll and were randomized to receive TBP or a readily available weight loss podcast. In mPOD, participants were required to own an internet-capable mobile device (Android, iPhone, iPod Touch, or Blackberry) to enroll and were randomized to receive either the TBP or TBP+mobile intervention. Because the control group in POD received a different podcast than the TBP groups and the TBP+mobile group, the POD control group was not included in these analyses. In both studies, participants were instructed to download two podcasts per week. In addition, those in the TBP+mobile group were instructed to download an promotion app, example here appreviewsubmit.com, to self-monitor diet and PA and to join Twitter so they could follow other participants, post messages, and read messages from group members and study counselors. Participants in both POD and mPOD attended an initial meeting after baseline data was completed in order to learn their random group assignment. Participants did not know each other prior to study enrollment. The online Twitter group for the TBP+mobile group included all members of the TBP+mobile group.
Participants in the TBP+mobile group were provided with a list of the Twitter user names for all TBP+mobile participants and were instructed to follow all the participants. Participants were free to create anonymous user names and use avatars which did not identify them. Participants were provided with an overview of how to download the Twitter app and post to Twitter at their orientation session. Participants were free to post as often as they liked and topics were not restricted. Study counselors posted messages (two/day), which reinforced the topics presented within the podcasts.
To standardize across groups for analysis, 3-month outcomes were used for both studies. Participants in both the POD and mPOD studies reported how they accessed the podcasts on a 3-month questionnaire by indicating which device was used most often to listen to the podcasts. Participants were classified by which method they used to access podcasts as mobile or non-mobile. In addition to self-report methods, in mPOD, objective podcast download data from the podcast hosting site was used to explore type of device downloading the data and to verify the self-report data. Objective download data was dichotomized as either mobile or non-mobile. Participants were also asked on the 3-month questionnaire where they were most often when they listened to the podcasts and what they were doing while listening to the podcasts. In addition, in mPOD, Twitter posts were coded for which type of method was primarily used for posting: mobile or non-mobile. Weight was assessed in both studies using a calibrated digital scale accurate to 0.1 kg at 3 months. Baseline weight values were carried forward for participants missing a 3-month weight assessment.