Longitudinal accuracy of web-based self-reported weights: Results from the hopkins power trial

Gerald J. Jerome, Arlene Dalcin, Janelle Coughlin, Stephanie Fitzpatrick, Nae Yuh Wang, Nowella Durkin, Hsin Chieh Yeh, Jeanne B Charleston, Thomas Pozefsky, Gail L Daumit, Jeanne Clark, Thomas Louis, Lawrence Appel

Research output: Contribution to journalArticle


Websites and phone apps are increasingly used to track weights during weight loss interventions, yet the longitudinal accuracy of these self-reported weights is uncertain. Objective: Our goal was to compare the longitudinal accuracy of self-reported weights entered online during the course of a randomized weight loss trial to measurements taken in the clinic. We aimed to determine if accuracy of self-reported weight is associated with weight loss and to determine the extent of misclassification in achieving 5% weight loss when using self-reported compared to clinic weights. Methods: This study examined the accuracy of self-reported weights recorded online among intervention participants in the Hopkins Practice-Based Opportunities for Weight Reduction (POWER) trial, a randomized trial examining the effectiveness of two lifestyle-based weight loss interventions compared to a control group among obese adult patients with at least one cardiovascular risk factor. One treatment group was offered telephonic coaching and the other group was offered in-person individual coaching and group sessions. All intervention participants (n=277) received a digital scale and were asked to track their weight weekly on a study website. Research staff used a standard protocol to measure weight in the clinic. Differences (self-reported weight- clinic weight) indicate if self-report under (-) or over (+) estimated clinic weight using the self-reported weight that was closest in time to the clinic weight and was within a window ranging from the day of the clinic visit to 7 days before the 6-month (n=225) and 24-month (n=191) clinic visits. The absolute value of the differences (absolute difference) describes the overall accuracy. Results: Underestimation of self-reported weights increased significantly from 6 months (mean-0.5kg, SD 1.0kg) to 24 months (mean-1.1kg, SD 2.0kg; P=.002). The average absolute difference also increased from 6 months (mean 0.7kg, SD 0.8kg) to 24 months (mean 1.3, SD 1.8kg; P

Original languageEnglish (US)
JournalJournal of Medical Internet Research
Issue number7
StatePublished - 2014



  • Internet
  • Obesity
  • Self-report
  • Weight loss

ASJC Scopus subject areas

  • Health Informatics
  • Medicine(all)

Cite this