Quality Control
As for the unification of study procedure and training, standardized training was provided to the researchers to familiarize them with all the procedures. Unified training was conducted to inform the participants of how the app should be used, how the corresponding questionnaires should be filled in, how relevant data should be uploaded, and the procedures they needed to follow. To avoid contamination between the different groups, remote dietary and physical interventions were conducted one-on-one through WeChat or telephone communication, rather than through the mobile phone app used in the study. In addition, the study participants could not register with the app by themselves. Registration had to be done by the background personnel, and an account number had to be provided before logging in. Therefore, the participants in groups DPI and PI could use the app, whereas those in group C could not. Throughout the trial, all the participants were prohibited from using health management apps or technologies other than the app in this study. After the study began, the entire process was strictly supervised and controlled by special quality-control researchers.