Using instrumented paper diaries to document self-monitoring patterns in weight loss.

Self-monitoring of eating is associated with successful weight loss, but adherence is imperfect and deteriorates over time. Moreover, intentionally or not, many individuals have difficulty keeping faithful records. We used instrumented paper diaries (IPDs) to study self-monitoring in randomly chosen participants in the PREFER trial, a behavioral treatment for weight-loss study. The diaries they used to self-report eating were periodically replaced with IPDs at various times during an 18-month weight-loss program, consisting of three successive phases: intense treatment (n=35), less-intense treatment (n=13), and maintenance (n=16). We compared electronically documented self-monitoring data, showing when and how often IPDs were used, with self-reported data, then compared the electronically validated adherence and weight loss. Self-reported diary usage exceeded IPD-documented usage while the electronic data demonstrated a significant decline in self-monitoring over time. Diary recording often was not timely. Percentage weight lost correlated significantly with frequency of IPD use (p=.001) and the number of diary entries made within 15 min of opening the IPD (p=.002). This is the first study to document patterns of self-monitoring among participants in a weight-loss program, which demonstrated that individuals may falsify the times and frequency of self-monitoring. Furthermore, our results showed that adherence to self-monitoring and the timeliness of recording significantly correlate with improved weight loss.