Introduction: Self-weighing is an important component of self-monitoring during weight loss. However, methods of measuring self-weighing frequency need to be validated. This analysis compared self-reported and objective weighing frequency. Methods: Data came from a 24-month randomized controlled trial. Participants received 12 months of a behavioral weight-loss program and were randomly assigned to (1) daily self-weighing, (2) weekly weighing, or (3) no weighing (excluded from analysis). Objective weighing frequency was measured by Wi-Fi enabled scales, and self-reported weighing frequency was assessed every 6 months by questionnaire. Objective weights were categorized to match the scale of the self-report measure. Results: At 12 months, there was 80.8% agreement between self-reported and objective weighing frequency (weighted kappa = 0.67; P < 0.001). At 24 months, agreement decreased to 48.5% (kappa = 0.27; P < 0.001). At both time points in which disagreements occurred, self-reported frequencies were generally greater than objectively assessed weighing. Both self-reported and objectively assessed weighing frequency was associated with weight loss at 12 and 24 months (P < 0.001). Conclusions: Self-reported weighing frequency is modestly correlated with objective weighing frequency; however, both are associated with weight change over time. Objective assessment of weighing frequency should be used to avoid overestimating actual frequency.
Bibliographical noteFunding Information:
Funding agencies: This research was supported by funding provided by National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) to JAL (R01DK093586). MMC was supported by a fellowship provided by NIDDK (T32DK083250), and KG was supported by a fellowship provided by the National Cancer Institute (T32CA193193). Disclosure: The authors declared no conflict of interest. Author contributions: MMC and JAL conceived of the presented idea. MMC conducted the analyses and developed the first draft of the manuscript. All authors reviewed and commented on subsequent drafts of the manuscript and provided approval of the final manuscript. Clinical trial registration: Clinical Trials.gov identifier NCT01646086. Received: 20 March 2018; Accepted: 19 May 2018; Published online: 1 August 2018. doi:10.1002/oby.22239