A Text Message-Based Intervention for Weight Loss: Randomized Controlled Trial

This paper describes the development and evaluation of a text message–based intervention designed to help individuals in the United States (US) change their eating behaviour in order to lose or maintain body weight. In that country, the percentage of overweight and obese adults increased from 43.3% in 1960 to 66.3% in 2003-04; obesity increases the risk of cardiovascular disease and overall mortality.

As detailed here, a database was developed of over 3,000 SMS (text) and MMS (multimedia - essentially, small pictures) messages and 1,500 rules that determined what message was sent based on the day of week, time of day, and the participant's eating behaviours and previous replies, among other parameters. The intervention was organised by topics that changed each week as the participant proceeded through the intervention. That is, the system was developed to be both personally tailored and interactive. For example, a participant who was identified as having difficulty eating fruits and vegetables might get the text message tip: "In a rush? Buy pre-cut vegetables like carrots, celery, and mushrooms for a quick, easy, and low calorie snack!" or the question "Did you buy fresh raw vegetables at the grocery store for snacks this week? (y/n)".

The study was a randomised controlled trial, with participants being exposed to one of the following 2 conditions, lasting 16 weeks: (i) receipt of monthly printed materials about weight control; and (ii) the intervention, which, as described above, included personalised SMS and MMS messages sent 2-5 times daily, as well as printed materials and brief monthly phone calls from a health counsellor. A total of 75 overweight men and women were randomised into one of the two groups, and 65 signed the consent form, completed the baseline questionnaire, and were included in the analysis. 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. Intervention participants' adjusted average weight loss was 2.88 kg (3.16%). At the end of the study, 22 of 24 (92%) intervention participants stated that they would recommend the intervention for weight control to friends and family.

The researchers conclude that text messages might prove to be a productive channel of communication to promote behaviours that support weight loss in overweight adults in the US.