The rates of overweight and obese US adults remain high, with 69% having a body mass index (BMI) greater than 25 kg/m2. Obesity and being overweight are associated with type 2 diabetes, cardiovascular disease, arthritis, asthma, and some cancers-thyroid, colon, breast (in postmenopausal women), endometrium, esophagus, and kidney. Mobile health (mHealth) holds promise as an effective method of delivering behavioral interventions addressing diet and physical activity, and it is less time-intensive than in-person, individual, or group sessions. Mobile phone ownership is pervasive; 85% of US adults report owning a mobile phone, with half owning smartphones. Smartphone ownership cuts across ethnic groups, with 49% of Hispanics, 47% of African Americans, and 42% of whites owning smartphones. While there has been emerging research in the area of using mHealth technologies to help people achieve a healthy weight, few studies have used an entirely mobile device-based approach to deliver a behavioral weight loss intervention. Frequent participant engagement with social media in the context of these weight loss interventions has been shown to be related to weight loss.
The Social POD App: An Overview
The Social Pounds Off Digitally (Social POD) app was developed by a transdisciplinary team of researchers including experts in health behavior, nutrition, computer science, psychology, exercise science, and social work. The overarching objective of this line of research has been to design an app that can be used to monitor and test scientific hypotheses related to optimal matching of participants to provide support for collective weight loss in the context of mobile interventions. The primary goal for this pilot study was to solicit participant feedback to refine the Social POD app for use in a larger pilot randomized clinical trial (RCT).
Pilot Study: Design and Participants
Men and women who were overweight or obese with Android smartphones (BMI 25-49.9 kg/m2; N=9) were recruited in South Carolina for a 2-month weight loss pilot intervention to test usability and provide feedback to be used in the refinement of the smartphone app. Participants were recruited via worksite listserv announcements, flyers, and newspaper advertisements. Exclusion criteria included not having an Android phone, previous stroke or heart attack diagnosis, diagnosis of diabetes and using insulin or oral medications to control diabetes, BMI outside the range of 25.0-49.9 kg/m2, unable to attend required meetings, unable to access the Internet using a computer for completing assessments, having a psychiatric illness, receiving treatment for drug or alcohol dependency, having an eating disorder, participating in another weight loss program, being pregnant or planning on becoming pregnant during the study, and breastfeeding. Participants were excluded for endorsing any of the first 4 items on the revised Physical Activity Readiness Questionnaire (PAR-Q): (1) informed by a doctor that they have a heart condition and should only participate in physical activities approved by a doctor, (2) feeling chest pain when engaging in physical activity, (3) experiencing chest pain in the past month when not engaging in physical activity, and (4) ever losing their balance and becoming dizzy or ever losing consciousness. If participants reported a bone or joint problem that could be made worse by participating in physical activity (item 5 of the PAR-Q) or taking blood pressure medication (item 6 of the PAR-Q), they were required to have a physician consent form completed to participate in the study.
Study Protocol
Participants attended 4 in-person meetings: an orientation session to learn about the study and complete baseline dietary assessments; a training session to learn how to download and use the Social POD app and podcasts and to collect baseline height and weight measurements; a mid-study focus group at 1 month to provide feedback regarding the usability of the Social POD app, provide suggestions for improvement, and collect 1-month weight measurements; and an end-of-study session to provide 2-month weight measurements. All participants provided written consent.
Participants were instructed to track their total calories from all meals, snacks, and beverages consumed; minutes of intentional physical activity; and body weight each day for the duration of the 2-month usability study. Participants were instructed to use MyFitnessPal or LoseIt, free commercial diet-tracking apps with extensive nutrient databases, to look up calorie information for food and beverages consumed. Participants were then asked to transfer total calories from each meal and snack consumed for the day to the Social POD app. Screenshots (left to right) of the home, meal tracking, and physical activity tracking screens on the Social POD app.
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Participants received within-app notifications at certain times throughout the day to remind them to self-monitor (promoting self-regulation) diet, minutes of physical activity, and total body weight each day. Participants could view a history of all dietary, activity, and weight information entered on the within-app history screen. Participants could view weight entered on a weight graph.
Re-engaging Infrequent Users
Participants who were frequently using the Social POD app (users who entered information in the app in the past 48 hours) were prompted via notifications to send encouraging messages to other group members who had not entered data in the app over the previous 48 hours (infrequent users). Messages were sent from frequent users by clicking the notification to send a message to an infrequent user, selecting one of three options listed on the message selection screen, and clicking Send. Screenshots (left to right) of the message log, message selection, and history screens on the Social POD app.
This study is novel in that it used theory-based messages designed by the researchers to help re-engage infrequent participants over the course of the 2-month intervention. Frequent users were randomly matched to provide support (by sending a theory-based message) to help re-engage infrequent users in this intervention. Social Cognitive Theory (SCT) was used as a framework to design user-to-user messages that targeted social support, self-efficacy, and outcome expectations regarding self-monitoring behavior (ie, targeting self-regulation) of diet, physical activity, and weight. SCT is the belief in the reciprocal relationship between cognitions, environmental influences, and behavior. Constructs from SCT were selected for this study based on results from a previous Internet-based weight loss intervention, which found that targeting these specific constructs led to healthier diet and physical activity behaviors and resulted in a reduction of body weight among study participants. The interventionists created messages for each of the three social construct theories and prompted frequent users to select 1 of 3 messages to send to an infrequent user. For example: “I found some light recipes on the Internet and they look pretty good. “Haven’t seen you log anything in the app lately.
Podcast Intervention
Participants were provided with 3 20-minute, evidence-based weight loss podcasts each week. Participants were instructed to listen to the 3 podcasts within the week but could listen at a time and place of their choosing. Podcasts were informed by SCT and provided participants with a range of weight loss topics. Podcast topics included nutrition and exercise information, an audio diary tracking the weight loss progress with challenges experienced by a male and female character, and a weight loss soap opera depicting the challenges of overcoming social barriers to weight loss, with a goal-setting activity related to weight loss at the end of each episode.
Data Collection
Participants completed online questionnaires assessing demographic characteristics. Height was measured at baseline assessment only using a Seca 213 (Hamburg, Germany) calibrated stadiometer. Weight was measured at baseline and 2 months using a Seca 869 calibrated digital scale accurate to 0.01 kg. Dietary measures were completed by participants using the National Cancer Institute’s Automated Self-Administered 24-Hour Dietary Recall (ASA24). Each participant completed the ASA24 online for 1 unannounced weekday and weekend day at baseline and 2 months. The following previously validated questionnaires were completed by participants at baseline and 2 months unless otherwise specified: the Paffenbarger Physical Activity Questionnaire to determine calories expended during activity, the 20-item Weight Efficacy-Lifestyle Questionnaire to measure participant self-efficacy, the 44-item Big Five Inventory (baseline only) as a measure of personality characteristics, and the Sallis Social Support Scale and Physical Activity Social Influence Scale as measures of social support from family and friends (modified to include online social networks). Objective measures of frequency and duration of app use were collected unobtrusively by a secure network server following the intervention (at 2 months).
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Qualitative Feedback: Focus Groups and Surveys
Participants attended 1 of 2 focus group sessions at 1 month to provide feedback regarding their use of the intervention components (Social POD app and podcasts). The focus groups were conducted by a trained focus group facilitator, and questions were asked using a semistructured interview guide developed by the investigators that included prescripted and spontaneous probes designed to elicit information from participants regarding their experience with the Social POD app. Questions were designed to assess participant satisfaction and dissatisfaction with the weight loss podcasts; the Social POD app including the tracking, prompting, and messaging features; and the weight graph and history features for future revisions. Participants were also asked if they would like incentives for using the app, and if so, how they would like an incentive system to be structured. Focus group sessions were taped using an audio recorder, and all participants were instructed to use their study identification number to protect confidentiality during the focus groups. A trained graduate research assistant was present at the focus group sessions to take field notes during the sessions. The focus group facilitator completed detailed memos following each midstudy focus group session to document salient themes from participant discussions.
During the study (weeks 1 through 7) participants completed brief weekly online surveys each Friday to report the number of podcasts listened to and the number of days they used the Social POD app that week. Participants also reported any problems experienced using the Social POD app during the past 7 days and any suggestions they had to improve the app. All qualitative data were collected and analyzed between February and August 2014 using NVivo for Mac Beta 2014 statistical software (QSR International) to extract a combination of a priori and emergent themes from the focus groups to guide the revision of the Social POD app. Open-ended responses from weekly surveys regarding problems experienced and suggestions for improvements to the Social POD app were coded as well.
Quantitative Analysis
Stata version 13.1 (StataCorp) software was used to detect statistical significance for all quantitative data analysis. Paired samples t test was used to test for statistically significant differences from pre- to posttest for weight, calories consumed, and calories expended during reported physical activity. The effect size for weight loss was also calculated. Correlation between total app entries and percent weight loss at 2 months was examined. Correlation between total days of objectively measured app use and total days of self-reported app use (via weekly questionnaires) by participants was examined. Fisher exact test was used, due to the small sample size, to detect significant differences in user-to-user message selection among participants categorized into subgroups based on amount of weight loss (dichotomized into groups of high versus low weight loss at the median split of percent weight loss). The sample size for this study was determined for qualitative analysis based on expert recommendations for mHealth usability testing studies; therefore, this study was not powered to detect significant changes in within-group weight. A total of 34 individuals inquired about the study, 15 individuals qualified to participate, and 9 completed baseline measures and received the intervention.
Key Findings
The analysis sought to answer the following questions: (1) What features of the Social POD app needed to be refined or developed to further incentivize participants to use the app? (2) Were there any significant changes from pre- to poststudy in participant weight, calories consumed, and reported intentional physical activity?
Participants lost a mean of 0.94 kg (SD 2.22, P=.24) and consumed significantly fewer kcals postintervention (1570 kcal/day, SD 508) as compared to baseline (2384 kcal/day, SD 993, P=.01). Participants reported expending a mean of 171 kcal/day (SD 153) during intentional physical activity following the intervention as compared to 138 kcal/day (SD 139) at baseline, yet this was not a statistically significant difference (P=.57). There was not a statistically significant correlation found between total app entries and percent weight loss over the course of the intervention (r=.49, P=.19). Mean number of app entries was 77.2 (SD 73.8) per person with a range of 0 to 219. Messages targeting social support were selected most often (32/68, 47%), followed by self-efficacy (28/68, 41%), and negative outcome expectations (8/68, 12%).
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The Significance of Social Support
The Social POD app provides an innovative way to re-engage infrequent users by encouraging frequent users to provide social support. The finding that messages targeting social support were selected most often highlights the importance of social connection in weight loss interventions. By leveraging the power of social networks, the Social POD app aims to create a supportive environment that encourages users to stay engaged and motivated in their weight loss journey.