Weight loss in Weight Watchers Online with and without an activity tracking device compared to control: A randomized trial

Objective To evaluate a commercial online weight loss program and activity tracker, which are popular but have unknown efficacy. Methods Two hundred seventy‐nine participants with BMI 27 to 40 kg/m 2 were randomized to 12 months of the Weight Watchers Online program alone (WWO) or with the ActiveLink ® activity tracking device (WWO+AL) or an online newsletter (Control). Results Weight losses at 3 months were significantly greater in WWO (2.7 kg [95% confidence interval (CI), 2.0‐3.5 kg] than Control (1.3 kg [95% CI, 0.5‐2.0 kg]; P  = 0.01); neither differed from WWO+AL (2.0 kg [95% CI, 1.3‐2.7 kg]; P s > 0.56). Significantly more WWO participants (24.5%) achieved ≥ 5% weight loss at 3 months than Control (9.4%) ( P  = 0.01); neither differed from WWO+AL (17.6%) ( Ps  = 0.13‐0.28). At 12 months, there were no significant differences between groups in weight loss ( P s > 0.52). WWO (25.5%) continued to have a higher proportion of participants achieving ≥ 5% weight loss than Control (12.9%) ( P  = 0.04); neither differed from WWO+AL (14.3%) ( P s > 0.10). There were no significant between‐group differences in change in physical activity ( P s > 0.17). Conclusions WWO produced significantly more weight loss at 3 months relative to Control, but not at 12 months. Significantly more WWO than Control participants lost ≥ 5% at both 3 and 12 months. Participants receiving an activity tracking device did not achieve greater weight loss or physical activity increases than those in a Control condition.