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Little is known about the feasibility and acceptability of tailored text message based weight loss programs for English and Spanish-language speakers.
This pilot study evaluated the feasibility, acceptability, and estimated impact of a tailored text message based weight loss program for English and Spanish-language speakers. The purpose of this pilot study was to inform the development of a full-scale randomized trial.
There were 20 overweight or obese participants (mean age 40.10, SD 8.05; 8/20, 40% male; 9/20, 45% Spanish-speakers) that were recruited in San Diego, California, from March to May 2011 and evaluated in a one-group pre/post clinical trial. For 8 weeks, participants received and responded to 3-5 text messages daily sent from a fully automated text messaging system. They also received printed weight loss materials and brief 10-15 minute weekly counseling calls. To estimate the impact of the program, the primary outcome was weight (kg) measured during face-to-face measurement visits by trained research staff. Pre and post differences in weight were analyzed with a one-way repeated measures analysis of variance. Differences by language preference at both time points were analyzed with
Participants who completed the final assessment (N
This fully automated text message based weight program was feasible with English and Spanish-speakers and may have promoted modest weight loss over an 8-week period.
Clinicaltrials.gov NCT01171586; http://clinicaltrials.gov/ct2/show/NCT01171586 (Archived by WebCite at http://www.webcitation.org/6Ksr6dl7n).
Text message based programs to promote behavior change are a rapidly growing area of research. This inexpensive, instantaneous, two-way communication of brief written messages via a mobile phone has many capabilities that may be useful for promoting weight loss. For example, texting features can support important constructs in behavior change theories such as cues to action, reinforcement, goal setting, goal reminders, and feedback. Text messages can be used as a stand-alone program [
This pilot study evaluated feasibility and acceptability of a tailored text message based weight loss program for English and Spanish-language speakers and enabled an estimate as to its impact on weight status. The purpose of this pilot study was to inform the development of a full-scale randomized trial.
We used an unblinded one-group pre/post design. The Institutional Review Board of University of California, San Diego (UCSD) approved this study. This manuscript is in accordance with the CONSORT-EHEALTH checklist [
Participants were recruited in San Diego, California, from March to May 2011 via newspapers, flyers, online announcements, and participant recommendations. The first 20 individuals who met the eligibility criteria were enrolled, with a goal of 40% (8/20) male and 50% (10/20) self-identified Spanish-speaking. Bilingual speakers choose language-message preference.
Eligible individuals were 21-60 years of age, had a body mass index (BMI) of 27.0-39.9, had a cellphone capable of sending and receiving text messages, were current users of texting or willing/able to learn, and could communicate in English or Spanish. Participants were excluded if they could not engage in moderate intensity PA, were pregnant or intended to become pregnant during the study, had a history of substance abuse or psychiatric disorders that would impair compliance, were using weight-altering medications, or were enrolled in another weight loss program. At baseline, potential participants were screened for inclusion and exclusion criteria and underwent written informed consent. Participants were compensated $75 for participation and $10 for a text message plan.
Social cognitive theory [
The 8-week intervention included: (1) 3-5 automatically scheduled and tailored text messages per day. Message content focused on diet and PA weight management behaviors and strategies; (2) a printed weight loss binder organized by weekly weight management topics such as portion control, increasing PA, reducing sedentary behavior, and self-monitoring; and (3) brief weekly 10-15 minute counseling calls to provide encouragement and reinforcement. A database was developed of more than 3000 text messages. The research group translated and culturally tailored the messages to Spanish-speakers to ensure linguistic and cultural equivalence. Approximately one-quarter of messages requested a reply, with the balance providing tips, suggestions, and positive reinforcement or encouragement for improved behaviors. The following shows sample messages sent and received from ConTxt (San Diego, CA 2011): (1) ConTxt–What is your weight today?, (2) Participant–220, (3) ConTxt–Congratulations! You have lost 5 lbs since starting ConTxt, (4) ConTxt–Here’s a healthy tip, put your pedometer on your nightstand so you can remember to put it on in the morning, (5) ConTxt–Work on your goal of reducing portion sizes this week by buying single serving pre-packaged snacks, and (6) ConTxt–Thank you. Your response has been recorded. A total of 1500 rules were added to control what message was sent based on the weekly behavioral strategy, day of the week, and time of day, as well as other parameters such as self-reported weight management behaviors and pedometer step count. A baseline dietary assessment of weight management behaviors was conducted using the Weight Behavior Inventory (WBI) to identify unique diet and PA behavior challenges for each participant contributing to high-energy intake and low-energy expenditure. A computerized expert system processed these data to create individualized goals based on predetermined logic rules. Goals were presented to the user via text message to serve as prompts for behavioral improvements. The system is designed so participants who show rapid and sustained progress can advance through content, while those experiencing difficulties can receive additional tips and suggestions.
Outcomes were measured at baseline and 8 weeks by trained research staff at UCSD research offices during face-to-face visits. The primary outcome was weight (kg) measured using a calibrated scale. Secondary measures included BMI calculated as kg/m2 and weight management behaviors associated with weight loss measured with the 35-item WBI (validation study under review, Kolodziejczyk et al 2013). The WBI was adapted from the validated Eating Behavior Inventory [
Feasibility and acceptability were measured by recruitment success, adherence, and participant satisfaction. Recruitment was deemed successful if we achieved our enrollment goal of 20 participants in two months. Adherence was measured by percentage of replies to interactive text messages (ie, text messages requesting a reply) and attrition rate. Satisfaction was measured using a Likert scale that asked about level of satisfaction with the program, as well as program components. In addition, we asked open-ended questions about elements of the program such as what they liked the least and best.
Pre and post differences between weight, BMI, and WBI scores were analyzed with one-way repeated measures analysis of variance. WBI score differences between gender and language preference at each time point were analyzed with independent sample
A total of 18 out of the 20 participants completed all measures (ie, two participants completed the program but did not show for their final assessment). On average, the sample was obese and had approximately equal percentages of participants across demographic categories.
Demographic characteristics of the ConTxt pilot participants (N=20).
Demographic variables | Overall sample | |
Age at study entry in years, mean (SD) | 40.10 (8.05) | |
BMI (kg/m2), mean (SD) | 33.67 (4.00) | |
Female, n (%) | 12 (60) | |
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Trade or technical school | 6 (30) |
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Some college | 2 (10) |
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College graduate | 3 (15) |
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Graduate degree | 7 (35) |
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“Prefer not to answer” | 2 (10) |
Married, n (%) | 11 (55) | |
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Hispanic | 15 (75) |
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White non-Hispanic | 13 (65) |
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Asian | 2 (10) |
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“Prefer not to answer” | 4 (20) |
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English | 11 (55) | |
Spanish | 9 (45) | |
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$1,000-1,999 | 5 (25) |
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$2,000-3,999 | 5 (25) |
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$4,000-5,999 | 6 (30) |
|
≥ $6,000 | 3 (15) |
“Don’t know/prefer not to answer” | 1 (5) |
aMore than one race category may apply
Participants decreased body weight by 1.85 kg (
Weight, BMI, and WBI from the ConTxt pilot study (San Diego, CA 2011) at baseline and 8 weeks (N=18).
Outcome | Baseline | 8 weeks | % Change |
Weight (kg)a, mean (SD) | 92.96 (39.65) | 91.11 (42.41)b | -1.99 |
BMI (kg/m2), mean (SD) | 33.78 (4.16) | 33.07 (4.45)b | -2.10 |
WBI score (points) | 2.11 (0.49) | 2.67 (0.37)c | 26.54 |
akg= kilograms
b
c
There was considerable interest in the study, as the recruitment goal of enrolling 20 participants in two months was achieved quickly after receiving 123 inquiries. Participants responded to 88.04% (986/1120) of interactive text messages, and there was a low 10% (2/20) attrition rate. Most participants (94%, 19/20) reported satisfaction with the program. Participants also reported the program helped motivate and reinforce healthier habits and choices (n=5), encouraged portion control and awareness of energy intake (n=4), and taught how to be more active (n=5). Some challenges participants reported included feelings of withdrawal after the program ended (n=7) and technical issues with their phone, which sometimes hindered message response (n=4).
An 8-week text message based weight loss program was found to be both feasible and acceptable in terms of recruitment interest, participant adherence, and satisfaction. The program may have had positive effects on weight management behaviors and weight outcomes, although this needs to be confirmed in a study with a stronger design. These results are consistent with previous text message based weight loss studies [
Study limitations include a small sample, a short time frame, and a one-group pre/post design. Therefore, our findings are suggestive rather than conclusive. Based upon these pilot study findings a full-scale randomized controlled trial currently is underway enrolling 298 participants for a one-year intervention.
body mass index
physical activity
University of California, San Diego
Weight Behavior Inventory
The National Cancer Institute (R01CA138730; Clinical Trial Registration: NCT01171586) supported this project. We gratefully acknowledge the support of everyone at the Center for Wireless & Population Health Systems.
Dr Patrick is co-owner of Santech, Inc, which is developing products related to the research described in this paper. Terms of this arrangement have been reviewed and approved by University of California, San Diego in accordance with their respective conflict of interest policies. Dr Norman, Dr Rock, and Mr Raab have received consulting income from Santech, Inc.