In behavioral weight loss (BWL) programs, self-monitoring (SM) is increasingly conducted with digital devices. This study was designed to fill gaps in the SM literature by 1) delivering a gold-standard BWL program in which participants were instructed to engage in digital SM of physical activity (PA), eating, and weight; 2) objectively measuring SM adherence; and 3) examining SM adherence as a predictor of weight and PA outcomes.


Participants (N = 87) were recruited from the community and provided with 12 weekly BWL group sessions. Participants were instructed to use a PA sensor and a digital app for recording food intake daily. They were asked to weigh themselves using a wireless scale weekly in weeks 1 to 10, and daily in weeks 11 and 12. Adherence to SM was assessed using data captured from participants’ three SM devices. Weight was measured in the clinic at weeks 0 and 12. PA was assessed with sensor data.


During the 12-week treatment period, participants wore their PA sensors and recorded food intake on 93.6% (±13.9%) and 91.5% (±12.6%) of days, respectively. Participants weighed themselves an average of twice per week when weekly SM of weight was prescribed. During weeks 11 and 12, when weight SM was to be conducted daily, participants self-weighed on an average of 72.8% of days (± 30.3%). Greater weight loss at week 12 was predicted by greater SM adherence in the domains of PA (p = .002), eating (p < .001), and weight (p < .001). Greater PA at 12 weeks also was predicted by greater SM of PA (p = .007) and eating (p < .001) but not weight (p = .236).


These data demonstrate that a high level of engagement can be reached when participants are instructed to use a suite of digital SM tools, with the caveat that more must be learned about barriers to daily SM of weight. Additional experimental research is needed to determine the extent to which adherence to digital SM directly improves outcomes, versus serves as a marker of adherence more generally.