A Mobile Health Intervention to Sustain Recent Weight Loss

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Background: Obesity is the number one health risk facing Americans. The obesity epidemic in America is attributed to physical inactivity, unhealthy food choices, and excessive food intake. Structured weight loss programs have been successful in initiating behavior change and weight loss; however, weight is almost always regained over time. The rate of weight gain is highest immediately after cessation of a structured weight loss program. Thus, effective interventions are needed that can successfully be used following a structured weight loss program to sustain weight loss and prevent weight relapse. Due to low cost, ubiquity, and ease of use, healthcare communicated through mobile technology, or "mHealth", may be able to serve as an effective medium to reach a large number of people to facilitate weight loss behaviors. Short message service (SMS), also known as text messaging, is easy to use, ubiquitous, affordable, and can target people directly where they are regardless of geographic location, socioeconomic status, or demographic factors. A review of the literature demonstrated limited information regarding message content, timing and frequency of message delivery and only 3 of 14 SMS-related interventions reviewed demonstrated a statistically significant effect on weight loss, diet or exercise. Additionally, information on how to integrate and leverage SMS as a health promotion tool for weight loss was also limited in the literature.

The Behavior Change Process model was used as a guide to understand how to develop an intervention to help people sustain recent weight loss. Furthermore, research suggests interventions that target and frame messages about how people reach goals in their life through either a prevention or promotion focus may be beneficial at motivating people to self-regulate and sustain recent behavioral changes. The goal of this study was to design an intervention that would help people stay in the continued response phase of the Behavior Change Process and help prevent weight relapse. Using the Behavior Change Process and regulatory focus theory, an intervention was developed that leveraged short message service (SMS) to deliver messages to people who have recently lost weight in attempt to help them sustain weight loss and prevent relapse.

Methods: First, a pilot study was conducted to inform the development of a SMS software application, the development of message content and the frequency and timing of message delivery. Second, an exploratory 3-arm mixed methods randomized controlled trial was conducted to test the feasibility, acceptability, perception of the usefulness, and efficacy of a weight loss sustaining mHealth SMS intervention among people with obesity. Participants (N=120) were randomized to a promotion message group, a prevention message group, or an attention-control general health message group. Participants completed baseline assessments, and reported their weight at 1 and 3 months post-baseline to assess efficacy of the intervention on sustaining weight loss. In addition, participants partook in a phone interview follow completion of the intervention to assess acceptability and usefulness.

Results: Participants found the message content and intervention acceptable and a majority perceived value in receiving messages via SMS that promote weight loss sustaining behaviors. Interview data implied that the intervention served as a reminder and daily cue to action. Participants were favorable towards receiving a daily reminder, which they noted helped them to stay focused, and in some cases to keep them motivated to continue losing weight. And a majority, 42 (91%) who participated in a telephone interview said that they preferred to get messages on their cell phone due to accessibility and convenience. A minimum of one message per day delivered at approximately 8:00 A.M. was deemed the optimal delivery time and frequency. This was particularly true for weight loss, which many participants reported as a daily struggle that begins every morning. With regards to sustaining weight loss, there was a statistical trend in sustained weight loss at months 1 and 3 in the promotion and prevention framed message groups compared to the control group in both the intent-to-treat and evaluable case analyses. Clinically, there was a significant decrease in mean weight of approximately 5 pounds at month 3 in the promotion and prevention groups compared to the control. Additionally, effect sizes indicated a large effect of the intervention on sustaining weight loss in the promotion and prevention groups relative to the control group.

Conclusion: Overall results showed that at the continued response phase of the behavioral change process, it was feasible to design an application to deliver promotion and prevention framed weight loss sustaining messages. In particular, prevention framed messages may have been more useful in helping participants sustain weight loss. Though there was less than 80% power to detect a statistically significant difference, the observed effect sizes in this study were significant and demonstrated a large effect of the promotion and prevention interventions on sustaining weight loss relative to control. Furthermore, there was a clinically significant increase in mean weight loss and in the number of people who sustained weight loss in the promotion and prevention intervention groups compared to control.

These findings may serve as a reference for future interventions designed to help people thwart relapse and transition from a state of sustaining recent weight loss behaviors to a state of maintenance. Technological tools such as this SMS intervention that are constructed and guided by evidence-based content and theoretical constructs show promise in helping people sustain healthy behaviors that can lead to improved health outcomes.






Shaw, Ryan J. (2012). A Mobile Health Intervention to Sustain Recent Weight Loss. Dissertation, Duke University. Retrieved from https://hdl.handle.net/10161/5866.


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