Coach access to digital self-monitoring data: an experimental test of short-term effects in behavioral weight-loss treatment

Objective: This study experimentally tested whether coach access to participants' digital self-monitoring data improved behavioral weight-loss outcomes. Methods: Participants (N = 322) received 12 weeks of group-based behavioral weight-loss sessions via videoconference and were instructed to engage in daily self-monitoring of weight, physical activity (PA), and dietary intake. For participants who were randomly assigned to Coach Share ON (n = 161), coaches regularly accessed a web-based portal that displayed data from the participants' scale, PA sensor, and food record. Results: Weight loss at 12 weeks was significantly greater in Coach Share ON versus OFF (6.2% vs. 5.3%; p = 0.04). Self-monitoring of PA (98.70% vs. 97.40% of days; p = 0.006) and eating (98.05% vs. 93.51% of days; p = 0.007) was more frequent in Coach Share ON versus OFF. There were no significant differences by condition in PA (p = 0.57), attendance (p = 0.42), working alliance (p = 0.62), or self-monitoring of weight (p = 0.12). Perceived supportive accountability was significantly greater in Coach Share ON versus OFF (p < 0.001). Conclusions: The short-term efficacy of behavioral weight loss was greater when coaches had direct access to self-monitoring device data. Notably, there also was no evidence of iatrogenic effects of data sharing.