JMIR Publications

ABSTRACT

Background:

Self-monitoring of lifestyle habits is the centerpiece of behavioral treatment for weight loss. The efficacy of smartphone-delivered feedback for self-monitoring of lifestyle behaviors in behavioral weight loss treatment has not been tested in large, long-term randomized clinical trials.

Objective:

To establish efficacy of providing remote feedback to self-monitoring of diet, physical activity and weight on improving weight loss outcomes at 12 months.

Methods:

DESIGN: Two-group, 12-month randomized controlled trial. SETTING: Single site, population-based study in southwest PA conducted between 2018 and 2021. PARTICIPANTS: Adults ≥18 years of age with a mean body mass index (BMI) between 27 and 43 kg/m2, who were smartphone users and able to engage in moderate physical activity (PA). INTERVENTION: All participants received a 90-minute 1:1 in-person behavioral weight loss counseling session that addressed behavioral strategies and established each participant’s daily dietary and weekly PA goals, and oriented them to the Fitbit Charge 2™, a smart scale, and a smartphone app to SM diet. Only SM+FB participants had access to an algorithm-based smartphone app that read the SM data and selected a tailored message that was sent to their phone up to 3 times daily. The SM only participants did not receive any feedback from the interventionists. MAIN OUTCOME(S) AND MEASURE(S): Percent weight change from baseline to 12 months. Secondary outcomes included adherence to the SM protocol and engagement with the mobile devices.

Results:

RESULTS: Participants (N = 502) were on average 45.0 (SD 14.4) years old with BMI of 33.7 (SD 4.0) kg/m2. The sample was 79.5% female (n = 399) and 82.5% white (n = 414). At 12 months, retention was 78.5% (n = 394) and similar by group (SM+FB: 80.5%, SM: 76.5%, P = .277) There was a significant percent weight loss from baseline in both groups (SM+FB: -2.12%, 95% CI, -3.04% to -1.21%, P < .0001; SM: -2.39%, 95% CI, -3.32% to -1.47%; P < .0001), but no difference between the groups (-0.27%; 95% CI, -1.57% to 1.03%, t-value = -0.41, P =.681). Similarly, clinically significant weight loss (≥5%) was achieved by 26.3% of the SM+FB group and 29.1% of the SM group (chi-square value = 0.49, P = .485. A one percent increase in FB messages opened was associated with 0.10 greater percent weight loss at 12 months (b=-0.10; 95% CI -0.13 to -0.07; t=-5.90; P<.0001).

Conclusions:

There were no significant between group differences in weight loss; however, results suggest that use of a tailored feedback intervention, as well as the use of commercially available digital self-monitoring tools without feedback, can result in a clinically significant weight loss in over 25% of participants. There was an association between opening feedback messages and weight loss. Clinical Trial: The study is registered with Clinicaltrials.gov (NCT03367936).