The increasing prevalence of overweight and obese adults in the United States has driven the need for innovative and accessible weight loss interventions. Even modest weight reduction-between 5 and 10% of body weight-in an overweight adult can reduce the risk of hypertension and diabetes. Among various approaches, weight loss text message programs have emerged as a promising strategy, leveraging the widespread use of mobile phones to deliver timely support and guidance. This article explores the effectiveness, implementation, and potential of weight loss text message programs, drawing on recent research and practical examples.
The Need for Accessible Weight Loss Solutions
To reach all 84.1 million US adults estimated to have prediabetes, low-cost and less burdensome alternatives to the National Diabetes Prevention Program (NDPP) are needed. A 2015 review found median costs of US $417 per person for programs comparable with the NDPP. A recent NDPP evaluation concluded that retention has been suboptimal, which may be because of the demands of year-long in-person meetings. Real-world NDPP implementation has appeared to result in less average weight loss (4.2% N=14,747 ) compared with that observed in its original RCT (4.9% N=1,079 ), along with concerning disparities in outcomes for underserved participants.
SMS4PreDM: A Case Study
One such program, SMS4PreDM, is a 12-month short message service (SMS) text message support program designed for individuals with prediabetes. SMS4PreDM methodology has been described in detail. In brief, SMS text message content was based on the NDPP curriculum and iteratively refined upon patient feedback. Messages promoted lifestyle change and modest weight loss and were delivered 6 days per week over 1 year. In a previous randomized controlled trial (RCT), SMS4PreDM demonstrated efficacy in individuals with prediabetes. Specifically, ≥3% weight loss was achieved by 30 of 79 or 38% of participants receiving the SMS4PreDM intervention (95% CI 27.7-49.3), compared with 17 of 81 or 21% of control group participants (95% CI 12.5-30.6; absolute difference of 17%; P=.02). Research suggests that such modest weight loss can prevent diabetes as every kilogram lost decreases risk by 16%.
A pragmatic study evaluated the implementation and effectiveness of SMS4PreDM in a safety net health care system. English- and Spanish-speaking patients at risk for diabetes (e.g., glycated hemoglobin 5.7-6.4) were referred by their providers and offered NDPP classes and/or SMS4PreDM. This analysis included 285 SMS4PreDM-only participants who began the intervention between October 2015 and April 2017, with accompanying baseline and follow-up weights available, as compared with a usual-care control group of 1233 patients at risk for diabetes and available weights, who were identified from electronic health record (EHR) data during the same time frame but not referred. Patients who became pregnant during the intervention or underwent bariatric surgery were excluded.
Evaluating the Effectiveness of SMS4PreDM
The study assessed weight outcomes including mean time-related weight change and realization of either ≥3% weight loss or gain. Mixed linear models adjusted for age, gender, race, ethnicity, preferred language, and baseline weight. A secondary analysis stratified by language. Implementation factors, including retention and cost, were also assessed.
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Retention in SMS4PreDM was high as only 20 of 285 or 7% dropped out in the first 4 weeks, with 259 of 285 or 91% completing the 12-month program. SMS4PreDM participants (n=285) had an average of 5.6 visits with weight assessments during the study period compared with 5.4 visits for the control group (n=1233; P=.72). Most SMS4PreDM participants (262 of 285 or 91.9%) exclusively had EHR-derived weights, with few patients having weights collected by invitation (23 of 285 or 8.1%).
The intervention group had a time-related mean weight loss of 1.3 pounds (SE 0.74), whereas the control group realized mean weight gain of 0.25 pounds (SE 0.59, P=.004). Spanish-speaking SMS4PreDM participants (n=130) realized time-related mean weight loss of 1.11 pounds (SE 1.22) compared with weight gain of 0.96 pounds (SE 1.14) in Spanish-speaking controls (n=382, P<.001). English-speaking intervention participants (n=155) did not achieve more time-related mean weight change (-0.89 pounds; SE 0.93) than English-speaking controls (n=828; 0.31 pounds gained; SE 0.62; P=.143). There was no significant difference between groups in frequency of reaching the ≥3% weight loss goal (54 of 285 or 19.0% of SMS4PreDM participants [95% CI 14.8-23.9] vs 266 of 1233 or 21.6% of controls [95% CI 19.3-24.0]; P=.33). However, more controls gained ≥3% weight compared with intervention participants (337 of 1233 or 27.3% of controls [95% CI 24.9-29.9] vs 57 of 285 or 20.0% of SMS4PreDM participants [95% CI 16.8-25.1]; P=.011). SMS4PreDM delivery costs were US $100.92 per participant.
Demographic Considerations
Demographic factors can influence the effectiveness of weight loss programs. The demographics of SMS4PreDM and control group participants revealed significant differences:
- Sex: Female participants were more prevalent in both the intervention (76.1%) and control groups (67.1%).
- Race: White participants constituted the majority in both groups (76.5% in the intervention group and 72.6% in the control group).
- Ethnicity: A higher proportion of participants in the intervention group identified as Hispanic/Latino (60.7%) compared to the control group (47.4%).
- Language: English was the preferred language for 54.4% of the intervention group and 67.2% of the control group, while Spanish was preferred by 45.6% and 30.9%, respectively.
- Age: The mean age was slightly lower in the intervention group (45.5 years) compared to the control group (48.4 years).
Text4Diet: Another Example of a Text-Based Intervention
Text4Diet is a lifestyle intervention aimed to promote modest levels of sustained weight loss. Users receive between 2 and 5 text messages per day depending on the frequency and schedule they choose. The messages contain tips, suggestions, and positive reinforcement or encouragement for improved behaviors; half of the text messages request the user to reply. The topics of the messages change weekly and contain behavioral and dietary strategies known to prompt weight loss and weight control. Topics include: goal setting, portion control, foods that are healthy and make one feel “full,” strategies for eating out and maintaining a physical activity regime. An example of a question sent to Text4Diet users is: “Did you buy fresh fruits and vegetables today?” If the user responds no, he or she will receive a follow-up message suggesting types of fruits and vegetables that can be added to a healthy and varied shopping list.
Users have a baseline dietary and lifestyle assessment conducted by a nutritionist or counselor and the results of this inform the type and content of the text messages that will be sent to the user. The users also receive a weekly text that tracks their weight and activity levels. Those who use Text4Diet are exposed to customized advice regarding healthy behavior changes. Participants on average saw an average 6-pound weight loss during a four-month use period. At the end of 4 months, the intervention group (n = 33) lost more weight than the comparison group (−1.97 kg difference, 95% CI −0.34 to −3.60 kg, P = .02) after adjusting for sex and age.
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Key Components of Effective Text Message Programs for Weight Loss
Several key components contribute to the success of text message programs for weight loss:
- Tailored Messaging: The program used a mobile phone-based application that delivered tailored and interactive messages important to weight loss, such as motivation, encouragement, progress, tips, and hints. This application consisted of a database of messages that were sent out to participants based on the frequency and type of messages participants wished to receive. Each week of the intervention focused on different topics related to weight loss, such as goal setting, portion control, physical activity, and strategies for eating out.
- Supplementary Materials: The intervention also included a binder with printed nutrition and health information to supplement the text messages. In addition, participants were also asked to weigh themselves and fill out worksheets weekly.
- Support System: This program targeted adults between the ages of 25 and 55 years old who were already overweight or obese and seeking to lose weight. In addition, the target population was already using or are willing to learn to use a mobile phone for text or multimedia messaging. The program was implemented and managed by health counselors and case managers. Health counselors played a crucial role in the conveying of important health information, while case managers focused on troubleshooting problems with the technical component of the intervention. The application had built in systems to monitor mistakes, anomalies, or unexpected responses from study participants and notify case managers who would then contact the study participant to address any problems or issues with the application.
- Accountability: Research consistently shows that people who have regular accountability are more likely to achieve their health goals. When you know you’ll be texting someone about your choices, you naturally make better decisions throughout the day. Daily accountability also helps identify patterns that weekly check-ins miss. Maybe you always struggle on Wednesdays because of work stress, or you eat differently on weekends.
Challenges and Limitations
Despite their potential, weight loss text message programs also face challenges and limitations:
- Modest Weight Loss Outcomes: In the SMS4PreDM study, modest weight outcomes suggest that SMS4PreDM may not be clinically effective enough to serve as a population health strategy. Although nearly twice as many SMS4PreDM participants achieved ≥3% weight loss than controls in our previously published RCT , less robust weight loss outcomes were demonstrated in real-world dissemination, a trend also observed with the NDPP .
- Nonrandomization: Limitations include nonrandomization in our pragmatic study, which may have contributed to demographic differences observed between study groups (although analyses controlled for such factors).
- Participant Compliance: Analyses also excluded participants without available weights; however, conditions for weight collection were largely similar between groups overall (eg, the majority of all patients in the analysis had weights collected from approximately bimonthly, routine clinical visits). However, a potential bias is that SMS4PreDM participants who successfully lost weight may have been more likely to comply with requests for final weight measurement with study personnel.
- Differential Response: It is also unknown why Spanish-speaking individuals appear to respond better to SMS text message support than English-speaking individuals, as consistent with our prior RCT .
Future Directions and Considerations
Future qualitative study may be needed to help explain why SMS4PreDM and similar interventions can yield less impact upon dissemination. Ensuring increased readiness for weight loss may potentially improve efficacy in a population that choose SMS text message support instead of in-person classes and possibly yield greater cost-effectiveness by more appropriately matching services with patients likely to benefit from them. Further research is also needed to better understand the extent to which supplemental coaching may be necessary to optimize weight loss and which extra-visit technology-based platforms (eg, apps) are most cost-effective.
Future efforts to target reach among Spanish speakers may also be merited, particularly given there is likely less-than-adequate availability of Spanish-language NDPPs or comparable in-person interventions. More broadly, SMS text messaging may be especially beneficial during the maintenance phase following weight loss, given its acceptability for long-term contact , coupled with modestly beneficial outcomes and a relatively low cost. Retention during the maintenance phase of the NDPP has been especially problematic , necessitating identification of retention-bolstering strategies.
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