Table 1.
Characteristics of the included studies on conversational agents (CAs) and chatbots for body weight management (N=8).
| Study and country | Study design | Participants | Mean (SD) age (years) | Main purpose of CA | Control group | Study duration |
| Wright et al [40], 2013, United States | RCTa | Youth-parent dyads with obesity from primary care (24/26b, 29 male and 21 female for youths, and 2 male and 48 female for parents) | 10.3 (1.1) for youths and 40.0 (9.1) for parents | Dietary modification and decrease in television time | A waitlist | 12 weeks |
| Stein and Brooks [20], 2017, United States | Uncontrolled before-and-after study | Adults with obesity or overweight from primary care (83c; NRd) | 46.9 (15.8) | Dietary modification | N/Ae | 15 weeks |
| Brust-Renck et al [38], 2017, United States | RCT | Healthy students interested in weight loss from 2 universities (37/183b; all female) | 19.2 (1.7) | Dietary modification and increase in physical activity | Tutorials on health topics other than obesity | 90 minutes |
| Kocielnik et al [42], 2018, United States | Uncontrolled before-and-after study | Active Fitbitf users (33; 4 male and 29 female) | 36.5 (11.2) | Increase in physical activity | N/A | 2 weeks |
| Stephens et al [39], 2019, United States | Uncontrolled before-and-after study | Youths with obesity from primary care (23; 10 male and 13 female) | 15.2 (NR) | Behavioral modification | N/A | 10-12 weeks |
| Maher et al [41], 2020, Australia | Uncontrolled before-and-after study | Inactive adults from the community (31; 10 male and 21 female) | 56.2 (8.0) | Dietary modification and increase in physical activity | N/A | 12 weeks |
| Piao et al [43], 2020, South Korea | RCT | Healthy office workers (57/49b; 25 male and 32 female/21 male and 28 femaleb) | NR | Increase in physical activity | No positive feedback from CA during the first 4 weeks | 12 weeks |
| To et al [44], 2021, Australia | Uncontrolled before-and-after study | Inactive adults recruited on the web (116; 21 male and 95 female) | 49.1 (9.3) | Increase in physical activity | N/A | 6 weeks |
aRCT: randomized controlled trial.
bExperimental group/control group.
cOf them, 70 were included in the data analysis.
dNR: not reported.
eN/A: not applicable.
fFitbit: commercial fitness-tracking tool.