Michelle I. Cardel

Objective The aim of this study was to identify the levels of food‐tracking adherence that best predict ≥3%, ≥5%, and ≥10% weight loss at 6 months and to identify distinctive food‐tracking trajectories among participants in a 6‐month, commercial digital weight‐management program. Methods This study used data from 153 participants of a single‐arm trial of a commercial digital weight‐management program, WeightWatchers (WW). Receiver operating characteristic (ROC) curve analysis was conducted to identify the optimum thresholds of food tracking that can predict ≥3%, ≥5%, and ≥10% weight loss at 6 months. Time series clustering analysis was performed on weekly food‐tracking data to identify trajectories and compare trajectories on weight loss at 6 months. Results ROC analyses showed that the optimum thresholds of food tracking were 28.5% of the intervention days to achieve ≥3% weight loss (area under the curve [AUC] = 0.820, p < 0.001), 39.4% to achieve ≥5% weight loss (AUC = 0.744, p < 0.001), and 67.1% to achieve 10% weight loss (AUC = 0.712, p = 0.002). Time series clustering analyses found three food‐tracking trajectories. Trajectories differed significantly in weight loss at 6 months ( F = 14.1, p < 0.001). Conclusions Results suggest that perfect food‐tracking adherence is not necessary to achieve clinically significant weight loss.