mDiet: A Text Message Intervention for Weight Loss

The SMS based intervention will be developed through formative research including focus groups, cognitive interviews, and a pilot test of a Spanish version of mDIET. The focus groups will be conducted with both English and Spanish speaking men and women to 1) learn more about the content areas to be addressed in the intervention including physical activity and sedentary behaviors to expand on previous research; 2) learn more about assessing equivalence and compatibility in intervention messages in English and Spanish; 3) identify the most culturally and linguistically appropriate messages; 4) assess text message use; 5) identify factors that influence food and physical activity decisions; and 6) identify health messages that Latinos see as most understandable, credible, and persuasive, cognitive interviews, and a pilot test of a Spanish version of mDIET. The cognitive interviews will be conducted in Spanish and will help inform translation of study materials (text messages and measures) from English to Spanish. An 8-week pilot test of the Latino (Spanish language) mDIET will be conducted to ensure that the text messages and SMS system works as expected in terms of usability and acceptability.

The randomized controlled trial will be a 12-month intervention with 309 study participants. Participants will be randomized to one of three groups: SMS-only, SMS plus phone counseling, and a control group (Details of the study arms are discussed in another section). The goals of the intervention groups (SMS-only and SMS plus phone counseling) include: 5% weight loss, 500 k/cal per day deficit through reduced caloric intake and increased energy expenditure, 12,00 steps through the use of a pedometer, and a reduction in sedentary behaviors. Participants will receive daily text messages, self-monitoring tools, and brief health promotion printed or wed materials on physical activity, nutrition, or other weight loss related topics. Participants will complete physiological and survey measures at baseline, 6 months, and 12 months to assess weight (BMI), physical activity and diet behaviors, psychosocial behaviors, environmental factors, and exposure and satisfaction with the program.

Inclusion criteria

• Are 21 - 60 years
• Are overweight or moderately obese with a BMI between 27.0 - 39.9
• Have a cell phone that is capable of sending and receiving text and picture messages
• Have a permanent residence in San Diego County and intend to stay over the entire study duration
• Speak and read English or Spanish
• Are willing to attend all (3) measurement assessments at the research office
• Provide assent and have a legal guardian that will participate and provide parental permission/consent

Exclusion criteria

• Have any of the following conditions: pulmonary, cardiovascular, or musculoskeletal problems that would limit the ability to comply with moderate intensity physical activity (i.e. brisk walking)
• Are pregnant or intend to become pregnant during the study period
• Have a history of substance abuse
• Have a psychiatric disorder that would impair compliance with the study protocol
• Are using weight loss medications or supplements
• Are currently involved in another weight loss study or program