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Professional dietary coaching within a group chat using a smartphone application for weight loss: a randomized controlled trial.

Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan, tanaka.kiyoji.ft@u.tsukuba.ac.jp. THF Co., Ltd, Tsukuba, Japan, tanaka.kiyoji.ft@u.tsukuba.ac.jp. Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan. Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Japan. Life Science Department, FiNC Inc., Tokyo, Japan. Genki Plaza Medical Center for Health Care, Tokyo, Japan. Faculty of Medicine, University of Tsukuba, Tsukuba, Japan.

Journal of multidisciplinary healthcare. 2018;:339-347
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Abstract

PURPOSE To test the effectiveness of professional dietary coaching via group chat using a smartphone application (app) for weight loss. METHODS This study was a 12-week, assessor-blind, parallel-group, waitlist-controlled randomized trial that included a 4-week follow-up period (trial registration, UMIN000025340). Data were collected between October 2016 and May 2017 and were analyzed between July 2017 and January 2018. Participants were 112 overweight, obese, or abdominally obese Japanese adults, aged 20 to 64 years, with at least one cardiometabolic risk factor. Participants were randomized to the coaching group (n=75) or control group (n=37), with a ratio of 2:1. The coaching group received a commercial weight loss program characterizing dietary coaching by a certified nutrition professional via group chat delivered on a smartphone app. Participants posted photos of every meal into the group chat, and the certified professional gave immediate direct feedback and encouragement. The primary outcome was an 8-week weight change. Secondary outcomes included 8-week changes in cardiometabolic risk factors. The frequency of meal photo uploads was recorded as a measure of adherence. RESULTS Of the 112 randomized participants, 93 (83.0%) and 81 (72.3%) completed 8-week and 12-week visits, respectively. Intention-to-treat analysis demonstrated significantly larger 8-week weight loss in the coaching group (-1.4 kg; 95% confidence interval [CI]: -2.0, -0.8 kg) than that in the control group (-0.1 kg; 95% CI: -0.6, 0.4 kg). Significantly larger improvements in triglyceride and glycated hemoglobin A1c levels were also obtained in the coaching group. These benefits, except for the triglyceride level, were maintained until week 12. The frequent upload of meal photos was associated with a larger 8-week weight loss in a dose-response fashion (P-value for trend <0.001). CONCLUSION This smartphone-delivered commercial weight loss program characterized as dietary coaching via group chat resulted in modest but significant weight loss. Facilitating participants' active involvement in the program is necessary to achieve greater health benefits.