Early weight loss in a standalone mHealth intervention predicting treatment success

Objective Early weight loss is a strong predictor of longer-term and clinically meaningful weight loss but has not been studied in the context of mobile health ('mHealth') interventions. Methods GoalTracker was a randomized trial among adults (21-65 years) with overweight or obesity comparing three 12-week standalone mHealth interventions for weight loss. All arms received a free commercial mobile app (MyFitnessPal) for daily self-monitoring of diet and/or weight and a goal to lose 5% of weight by 3 months. Collapsing across arms, this analysis examined participants with a 1-month weight (n = 84), categorizing them as either early responders (>= 2% weight loss at 1 month) or early non-responders (<2% weight loss at 1 month). Results Early responders - 36% of participants - had greater per cent weight change at 3 months (-5.93% [95% confidence interval: -6.82%, -5.03%]) than early non-responders (-1.45% [-2.15%, -0.75%]), which was sustained at 6 months (-5.91% [-7.33%, -4.48%] vs. -1.28% [-2.37%, -0.19%]; ps < 0.0001). Over half (57%) of early responders achieved >= 5% weight loss at 3 months vs. 11% of early non-responders. At 4 weeks, self-monitoring frequency (weight/diet) was significantly greater among early responders, which continued across 12 weeks. Conclusion Responding early to an mHealth treatment is associated with higher engagement and greater likelihood of achieving clinically meaningful weight loss.